Chapter 21 - Standard Template Library 1 (STL)

Outline 21.1 Introduction to the Standard Template Library (STL) 21.1.1 Introduction to Containers 21.1.2 Introduction to Iterators 21.1.3 Introduction to Algorithms 21.2 Sequence Containers 21.2.1 vector Sequence Container 21.2.2 list Sequence Container 21.2.3 deque Sequence Container 21.3 Associative Containers 21.3.1 multiset Associative Container 21.3.2 set Associative Container 21.3.3 multimap Associative Container 21.3.4 map Associative Container 21.4 Container Adapters 21.4.1 stack Adapter 21.4.2 queue Adapter 21.4.3 priority_queue Adapter

21.5 Algorithms 21.5.1 fill, fill_n, generate and generate_n 21.5.2 equal, mismatch and lexicographical_compare 21.5.3 remove, remove_if, remove_copy and remove_copy_if 21.5.4 replace, replace_if, replace_copy and replace_copy_if 21.5.5 Mathematical Algorithms 21.5.6 Basic Searching and Sorting Algorithms 21.5.7 swap, iter_swap and swap_ranges 21.5.8 copy_backward, merge, unique and reverse 21.5.9 inplace_merge, unique_copy and reverse_copy 21.5.10 Set Operations 21.5.11 lower_bound, upper_bound and equal_range 21.5.12 Heapsort 21.5.13 min and max 21.5.14 Algorithms Not Covered in This Chapter 21.6 Class bitset 21.7 Function Objects

 2003 Prentice Hall, Inc. All rights reserved. 3 21.1 Introduction to the Standard Template Library (STL) • STL – Powerful, template-based components • Containers: template data structures • Iterators: like pointers, access elements of containers • Algorithms: data manipulation, searching, sorting, etc. – Object- oriented programming: reuse, reuse, reuse – Only an introduction to STL, a huge class library

• Three types of containers – Sequence containers • Linear data structures (vectors, linked lists) • First-class container – Associative containers • Non-linear, can find elements quickly • Key/value pairs • First-class container – Container adapters • Near containers – Similar to containers, with reduced functionality • Containers have some common functions

• Sequence containers – vector – deque – list • Associative containers – set – multiset – map – multimap • Container adapters – stack – queue – priority_queue

• Member functions for all containers – Default constructor, copy constructor, destructor – empty – max_size, size – = < <= > >= == != – swap • Functions for first-class containers – begin, end – rbegin, rend – erase, clear

• typedefs for first-class containers – value_type – reference – const_reference – pointer – iterator – const_iterator – reverse_iterator – const_reverse_iterator – difference_type – size_type

• Iterators similar to pointers – Point to first element in a container – Iterator operators same for all containers • * dereferences • ++ points to next element • begin() returns iterator to first element • end() returns iterator to last element – Use iterators with sequences (ranges) • Containers • Input sequences: istream_iterator • Output sequences: ostream_iterator

• Usage – std::istream_iterator< int > inputInt( cin ) • Can read input from cin • *inputInt – Dereference to read first int from cin • ++inputInt – Go to next int in stream – std::ostream_iterator< int > outputInt(cout) • Can output ints to cout • *outputInt = 7 – Outputs 7 to cout • ++outputInt – Advances iterator so we can output next int

 2003 Prentice Hall, Inc. All rights reserved. 10 1 // Fig. 21.5: fig21_05.cpp Outline 2 // Demonstrating input and output with iterators. 3 #include 4 fig21_05.cpp 5 using std::cout; (1 of 2) 6 using std::cin; 7 using std::endl; 8 Note creation of 9 #include // ostream_iteratoristream_iterator and istream_iterator. For 10 compilation reasons, we use 11 int main() std:: rather than a using 12 { statement. 13 cout << "Enter two integers: "; Access and assign the iterator 14 like a pointer. 15 // create istream_iterator for reading int values from cin 16 std::istream_iterator< int > inputInt( cin ); 17 18 int number1 = *inputInt; // read int from standard input 19 ++inputInt; // move iterator to next input value 20 int number2 = *inputInt; // read int from standard input 21

 2003 Prentice Hall, Inc. All rights reserved. 11 22 // create ostream_iterator for writing int values to cout Outline 23 std::ostream_iterator< int > outputInt( cout ); 24 25 cout << "The sum is: "; fig21_05.cpp 26 *outputInt = number1 + number2; // output result to cout (2 of 2) 27 cout << endl; 28 fig21_05.cpp 29 return 0; output (1 of 1) 30 31 } // end main

Enter two integers: 12 25 The sum is: 37 Create an ostream_iterator is similar. Assigning to this iterator outputs to cout.

• Input – Read elements from container, can only move forward • Output – Write elements to container, only forward • Forward – Combines input and output, retains position – Multi-pass (can pass through sequence twice) • Bidirectional – Like forward, but can move backwards as well • Random access – Like bidirectional, but can also jump to any element

• Sequence containers – vector: random access – deque: random access – list: bidirectional • Associative containers (all bidirectional) – set – multiset – Map – multimap • Container adapters (no iterators supported) – stack – queue – priority_queue

• All – ++p, p++ • Input iterators – *p – p = p1 – p == p1, p != p1 • Output iterators – *p – p = p1 • Forward iterators – Have functionality of input and output iterators

• Bidirectional – --p, p-- • Random access – p + i, p += i – p - i, p -= i – p[i] – p < p1, p <= p1 – p > p1, p >= p1

• STL has algorithms used generically across containers – Operate on elements indirectly via iterators – Often operate on sequences of elements • Defined by pairs of iterators • First and last element – Algorithms often return iterators • find() • Returns iterator to element, or end() if not found – Premade algorithms save programmers time and effort

• Three sequence containers – vector - based on arrays – deque - based on arrays – list - robust linked list

• vector – – Data structure with contiguous memory locations • Access elements with [] – Use when data must be sorted and easily accessible • When memory exhausted – Allocates larger, contiguous area of memory – Copies itself there – Deallocates old memory • Has random access iterators

• Declarations – std::vector v; • type: int, float, etc. • Iterators – std::vector::const_iterator iterVar; • const_iterator cannot modify elements – std::vector::reverse_iterator iterVar; • Visits elements in reverse order (end to beginning) • Use rbegin to get starting point • Use rend to get ending point

• vector functions – v.push_back(value) • Add element to end (found in all sequence containers). – v.size() • Current size of vector – v.capacity() • How much vector can hold before reallocating memory • Reallocation doubles size – vector v(a, a + SIZE) • Creates vector v with elements from array a up to (not including) a + SIZE

• vector functions – v.insert(iterator, value ) • Inserts value before location of iterator – v.insert(iterator, array , array + SIZE) • Inserts array elements (up to, but not including array + SIZE) into vector – v.erase( iterator ) • Remove element from container – v.erase( iter1, iter2 ) • Remove elements starting from iter1 and up to (not including) iter2 – v.clear() • Erases entire container

• vector functions operations – v.front(), v.back() • Return first and last element – v.[elementNumber] = value; • Assign value to an element – v.at[elementNumber] = value; • As above, with range checking • out_of_bounds exception

• ostream_iterator – std::ostream_iterator< type > Name ( outputStream, separator ); • type: outputs values of a certain type • outputStream: iterator output location • separator: character separating outputs • Example – std::ostream_iterator< int > output( cout, " " ); – std::copy( iterator1, iterator2, output ); • Copies elements from iterator1 up to (not including) iterator2 to output, an ostream_iterator

 2003 Prentice Hall, Inc. All rights reserved. 24 1 // Fig. 21.14: fig21_14.cpp Outline 2 // Demonstrating standard library vector class template. 3 #include 4 fig21_14.cpp 5 using std::cout; (1 of 3) 6 using std::cin; 7 using std::endl; 8 9 #include // vector class-template definition 10 11 // prototype for function template printVector 12 template < class T > 13 void printVector( const std::vector< T > &integers2 ); 14 15 int main() 16 { Create a vector of ints. 17 const int SIZE = 6; 18 int array[ SIZE ] = { 1, 2, 3, 4, 5, 6 }; Call member functions. 19 20 std::vector< int > integers; 21 22 cout << "The initial size of integers is: " 23 << integers.size() 24 << "\nThe initial capacity of integers is: " 25 << integers.capacity(); 26

 2003 Prentice Hall, Inc. All rights reserved. 25 27 // function push_back is in every sequence collection Add elements to end of Outline 28 integers.push_back( 2 ); 29 integers.push_back( 3 ); vector using push_back. 30 integers.push_back( 4 ); fig21_14.cpp 31 (2 of 3) 32 cout << "\nThe size of integers is: " << integers.size() 33 << "\nThe capacity of integers is: " 34 << integers.capacity(); 35 36 cout << "\n\nOutput array using pointer notation: "; 37 38 for ( int *ptr = array; ptr != array + SIZE; ++ptr ) 39 cout << *ptr << ' '; 40 41 cout << "\nOutput vector using iterator notation: "; 42 printVector( integers ); 43 44 cout << "\nReversed contents of vector integers: "; 45

 2003 Prentice Hall, Inc. All rights reserved. 26 46 std::vector< int >::reverse_iterator reverseIterator; Outline 47 48 for ( reverseIterator = integers.rbegin(); 49 reverseIterator!= integers.rend(); Walk through vectorfig21_ 14.cpp 50 ++reverseIterator ) backwards using (a3 of 3) 51 cout << *reverseIterator << ' '; reverse_iterator. 52 53 cout << endl; 54 55 return 0; 56 57 } // end main Template function to walk 58 through vector forwards. 59 // function template for outputting vector elements 60 template < class T > 61 void printVector( const std::vector< T > &integers2 ) 62 { 63 std::vector< T >::const_iterator constIterator; 64 65 for ( constIterator = integers2.begin(); 66 constIterator != integers2.end(); 67 constIterator++ ) 68 cout << *constIterator << ' '; 69 70 } // end function printVector

 2003 Prentice Hall, Inc. All rights reserved. 27 The initial size of v is: 0 Outline The initial capacity of v is: 0 The size of v is: 3 The capacity of v is: 4 fig21_14.cpp output (1 of 1) Contents of array a using pointer notation: 1 2 3 4 5 6 Contents of vector v using iterator notation: 2 3 4 Reversed contents of vector v: 4 3 2

 2003 Prentice Hall, Inc. All rights reserved. 28 1 // Fig. 21.15: fig21_15.cpp Outline 2 // Testing Standard Library vector class template 3 // element-manipulation functions. 4 #include fig21_15.cpp 5 (1 of 3) 6 using std::cout; 7 using std::endl; 8 9 #include // vector class-template definition 10 #include // copy algorithm 11 12 int main() Create vector (initialized 13 { using an array) and 14 const int SIZE = 6; . 15 int array[ SIZE ] = { 1, 2, 3, 4, 5, 6 }; ostream_iterator 16 17 std::vector< int > integers( array, array + SIZE ); Copy range of iterators to output 18 std::ostream_iterator< int > output( cout, " " ); (ostream_iterator). 19 20 cout << "Vector integers contains: "; 21 std::copy( integers.begin(), integers.end(), output ); 22 23 cout << "\nFirst element of integers: " << integers.front() 24 << "\nLast element of integers: " << integers.back(); 25

 2003 Prentice Hall, Inc. All rights reserved. 29 26 integers[ 0 ] = 7; // set first element to 7 Outline 27 integers.at( 2 ) = 10; // set element at position 2 to 10 28 29 // insert 22 as 2nd element More vector membfiger2 1_15.cpp 30 integers.insert( integers.begin() + 1, 22 ); functions. (2 of 3) 31 32 cout << "\n\nContents of vector integers after changes: "; 33 std::copy( integers.begin(), integers.end(), output ); 34 at has range checking, and 35 // access out-of-range element can throw an exception. 36 try { 37 integers.at( 100 ) = 777; 38 39 } // end try 40 41 // catch out_of_range exception 42 catch ( std::out_of_range outOfRange ) { 43 cout << "\n\nException: " << outOfRange.what(); 44 45 } // end catch 46 47 // erase first element 48 integers.erase( integers.begin() ); 49 cout << "\n\nVector integers after erasing first element: "; 50 std::copy( integers.begin(), integers.end(), output ); 51

 2003 Prentice Hall, Inc. All rights reserved. 30 52 // erase remaining elements Outline 53 integers.erase( integers.begin(), integers.end() ); 54 cout << "\nAfter erasing all elements, vector integers " 55 << ( integers.empty() ? "is" : "is not" ) << " empty"; fig21_15.cpp 56 (3 of 3) 57 // insert elements from array 58 integers.insert( integers.begin(), array, array + SIZE ); 59 cout << "\n\nContents of vector integers before clear: "; 60 std::copy( integers.begin(), integers.end(), output ); 61 62 // empty integers; clear calls erase to empty a collection 63 integers.clear(); 64 cout << "\nAfter clear, vector integers " 65 << ( integers.empty() ? "is" : "is not" ) << " empty"; 66 67 cout << endl; 68 69 return 0; 70 71 } // end main

 2003 Prentice Hall, Inc. All rights reserved. 31 Vector integers contains: 1 2 3 4 5 6 Outline First element of integers: 1 Last element of integers: 6 fig21_15.cpp Contents of vector integers after changes: 7 22 2 10 4 5 6 output (1 of 1)

Exception: invalid vector subscript

Vector integers after erasing first element: 22 2 10 4 5 6 After erasing all elements, vector integers is empty

Contents of vector integers before clear: 1 2 3 4 5 6 After clear, vector integers is empty

• list container – Header – Efficient insertion/deletion anywhere in container – Doubly-linked list (two pointers per node) – Bidirectional iterators – std::list< type > name;

• list functions for object t – t.sort() • Sorts in ascending order – t.splice(iterator, otherObject ); • Inserts values from otherObject before iterator – t.merge( otherObject ) • Removes otherObject and inserts it into t, sorted – t.unique() • Removes duplicate elements

• list functions – t.swap(otherObject); • Exchange contents – t.assign(iterator1, iterator2) • Replaces contents with elements in range of iterators – t.remove(value) • Erases all instances of value

 2003 Prentice Hall, Inc. All rights reserved. 35 1 // Fig. 21.17: fig21_17.cpp Outline 2 // Standard library list class template test program. 3 #include 4 fig21_17.cpp 5 using std::cout; (1 of 5) 6 using std::endl; 7 8 #include // list class-template definition 9 #include // copy algorithm 10 11 // prototype for function template printList 12 template < class T > 13 void printList( const std::list< T > &listRef ); 14 15 int main() 16 { Create two list objects. 17 const int SIZE = 4; 18 int array[ SIZE ] = { 2, 6, 4, 8 }; 19 20 std::list< int > values; 21 std::list< int > otherValues; 22 23 // insert items in values 24 values.push_front( 1 ); 25 values.push_front( 2 ); 26 values.push_back( 4 ); 27 values.push_back( 3 );  2003 Prentice Hall, Inc. All rights reserved. 36 28 Various member Outline 29 cout << "values contains: "; list 30 printList( values ); functions. 31 fig21_17.cpp 32 values.sort(); // sort values (2 of 5) 33 34 cout << "\nvalues after sorting contains: "; 35 printList( values ); 36 37 // insert elements of array into otherValues 38 otherValues.insert( otherValues.begin(), 39 array, array + SIZE ); 40 41 cout << "\nAfter insert, otherValues contains: "; 42 printList( otherValues ); 43 44 // remove otherValues elements and insert at end of values 45 values.splice( values.end(), otherValues ); 46 47 cout << "\nAfter splice, values contains: "; 48 printList( values ); 49 50 values.sort(); // sort values 51 52 cout << "\nAfter sort, values contains: "; 53 printList( values ); 54  2003 Prentice Hall, Inc. All rights reserved. 37 55 // insert elements of array into otherValues Outline 56 otherValues.insert( otherValues.begin(), 57 array, array + SIZE ); 58 otherValues.sort(); fig21_17.cpp 59 (3 of 5) 60 cout << "\nAfter insert, otherValues contains: "; 61 printList( otherValues ); 62 63 // remove otherValues elements and insert into values 64 // in sorted order 65 values.merge( otherValues ); 66 67 cout << "\nAfter merge:\n values contains: "; 68 printList( values ); 69 cout << "\n otherValues contains: "; 70 printList( otherValues ); 71 72 values.pop_front(); // remove element from front 73 values.pop_back(); // remove element from back 74 75 cout << "\nAfter pop_front and pop_back:" 76 << "\n values contains: "; 77 printList( values ); 78 79 values.unique(); // remove duplicate elements 80 81 cout << "\nAfter unique, values contains: ";  2003 Prentice Hall, Inc. 82 printList( values ); All rights reserved. 38 83 Outline 84 // swap elements of values and otherValues 85 values.swap( otherValues ); 86 fig21_17.cpp 87 cout << "\nAfter swap:\n values contains: "; (4 of 5) 88 printList( values ); 89 cout << "\n otherValues contains: "; 90 printList( otherValues ); 91 92 // replace contents of values with elements of otherValues 93 values.assign( otherValues.begin(), otherValues.end() ); 94 95 cout << "\nAfter assign, values contains: "; 96 printList( values ); 97 98 // remove otherValues elements and insert into values 99 // in sorted order 100 values.merge( otherValues ); 101 102 cout << "\nAfter merge, values contains: "; 103 printList( values ); 104 105 values.remove( 4 ); // remove all 4s 106 107 cout << "\nAfter remove( 4 ), values contains: "; 108 printList( values );

 2003 Prentice Hall, Inc. All rights reserved. 39 109 Outline 110 cout << endl; 111 112 return 0; fig21_17.cpp 113 (5 of 5) 114 } // end main 115 116 // printList function template definition; uses 117 // ostream_iterator and copy algorithm to output list elements 118 template < class T > 119 void printList( const std::list< T > &listRef ) 120 { 121 if ( listRef.empty() ) 122 cout << "List is empty"; 123 124 else { 125 std::ostream_iterator< T > output( cout, " " ); 126 std::copy( listRef.begin(), listRef.end(), output ); 127 128 } // end else 129 130 } // end function printList

 2003 Prentice Hall, Inc. All rights reserved. 40 values contains: 2 1 4 3 Outline values after sorting contains: 1 2 3 4 After insert, otherValues contains: 2 6 4 8 After splice, values contains: 1 2 3 4 2 6 4 8 fig21_17.cpp After sort, values contains: 1 2 2 3 4 4 6 8 output (1 of 1) After insert, otherValues contains: 2 4 6 8 After merge: values contains: 1 2 2 2 3 4 4 4 6 6 8 8 otherValues contains: List is empty After pop_front and pop_back: values contains: 2 2 2 3 4 4 4 6 6 8 After unique, values contains: 2 3 4 6 8 After swap: values contains: List is empty otherValues contains: 2 3 4 6 8 After assign, values contains: 2 3 4 6 8 After merge, values contains: 2 2 3 3 4 4 6 6 8 8 After remove( 4 ), values contains: 2 2 3 3 6 6 8 8

• deque ("deek"): double-ended queue – Header – Indexed access using [] – Efficient insertion/deletion in front and back – Non-contiguous memory: has "smarter" iterators • Same basic operations as vector – Also has • push_front (insert at front of deque) • pop_front (delete from front)

 2003 Prentice Hall, Inc. All rights reserved. 42 1 // Fig. 21.18: fig21_18.cpp Outline 2 // Standard library class deque test program. 3 #include 4 fig21_18.cpp 5 using std::cout; (1 of 2) 6 using std::endl; 7 8 #include // deque class-template definition 9 #include // copy algorithmCreate a deque, use member 10 functions. 11 int main() 12 { 13 std::deque< double > values; 14 std::ostream_iterator< double > output( cout, " " ); 15 16 // insert elements in values 17 values.push_front( 2.2 ); 18 values.push_front( 3.5 ); 19 values.push_back( 1.1 ); 20 21 cout << "values contains: "; 22 23 // use subscript operator to obtain elements of values 24 for ( int i = 0; i < values.size(); ++i ) 25 cout << values[ i ] << ' '; 26

 2003 Prentice Hall, Inc. All rights reserved. 43 27 values.pop_front(); // remove first element Outline 28 29 cout << "\nAfter pop_front, values contains: "; 30 std::copy( values.begin(), values.end(), output ); fig21_18.cpp 31 (2 of 2) 32 // use subscript operator to modify element at location 1 33 values[ 1 ] = 5.4; fig21_18.cpp 34 output (1 of 1) 35 cout << "\nAfter values[ 1 ] = 5.4, values contains: "; 36 std::copy( values.begin(), values.end(), output ); 37 38 cout << endl; 39 40 return 0; 41 42 } // end main values contains: 3.5 2.2 1.1 After pop_front, values contains: 2.2 1.1 After values[ 1 ] = 5.4, values contains: 2.2 5.4

• Associative containers – Direct access to store/retrieve elements – Uses keys (search keys) – 4 types: multiset, set, multimap and map • Keys in sorted order • multiset and multimap allow duplicate keys • multimap and map have keys and associated values • multiset and set only have values

• multiset – Header – Fast storage, retrieval of keys (no values) – Allows duplicates – Bidirectional iterators • Ordering of elements – Done by comparator function object • Used when creating multiset – For integer multiset • less comparator function object • multiset< int, std::less > myObject; • Elements will be sorted in ascending order

• Multiset functions – ms.insert(value) • Inserts value into multiset – ms.count(value) • Returns number of occurrences of value – ms.find(value) • Returns iterator to first instance of value – ms.lower_bound(value) • Returns iterator to first location of value – ms.upper_bound(value) • Returns iterator to location after last occurrence of value

• Class pair – Manipulate pairs of values – Pair objects contain first and second • const_iterators – For a pair object q q = ms.equal_range(value) • Sets first and second to lower_bound and upper_bound for a given value

 2003 Prentice Hall, Inc. All rights reserved. 48 1 // Fig. 21.19: fig21_19.cpp Outline 2 // Testing Standard Library class multiset 3 #include 4 fig21_19.cpp 5 using std::cout; (1 of 3) 6 using std::endl; 7 typedefs help clarify 8 #include // multiset class-template definition program. This declares an 9 integer multiset that stores 10 // define short name for multiset type used in this programvalues in ascending order. 11 typedef std::multiset< int, std::less< int > > ims; 12 13 #include // copy algorithm 14 15 int main() 16 { 17 const int SIZE = 10; 18 int a[ SIZE ] = { 7, 22, 9, 1, 18, 30, 100, 22, 85, 13 }; 19 20 ims intMultiset; // ims is typedef for "integer multiset" 21 std::ostream_iterator< int > output( cout, " " ); 22 23 cout << "There are currently " << intMultiset.count( 15 ) 24 << " values of 15 in the multiset\n"; 25

 2003 Prentice Hall, Inc. All rights reserved. 49 26 intMultiset.insert( 15 ); // insert 15 in intMultiset Outline 27 intMultiset.insert( 15 ); // insert 15 in intMultiset 28 29 cout << "After inserts, there are " fig21_19.cpp 30 << intMultiset.count( 15 ) (2 of 3) 31 << " values of 15 in the multiset\n\n"; 32 33 // iterator that cannot be used to change elementUse m emvaluesber function find. 34 ims::const_iterator result; 35 36 // find 15 in intMultiset; find returns iterator 37 result = intMultiset.find( 15 ); 38 39 if ( result != intMultiset.end() ) // if iterator not at end 40 cout << "Found value 15\n"; // found search value 15 41 42 // find 20 in intMultiset; find returns iterator 43 result = intMultiset.find( 20 ); 44 45 if ( result == intMultiset.end() ) // will be true hence 46 cout << "Did not find value 20\n"; // did not find 20 47 48 // insert elements of array a into intMultiset 49 intMultiset.insert( a, a + SIZE ); 50 51 cout << "\nAfter insert, intMultiset contains:\n"; 52 std::copy( intMultiset.begin(), intMultiset.end(), output ); 53  2003 Prentice Hall, Inc. All rights reserved. 50 54 // determine lower and upper bound of 22 in intMultiset Outline 55 cout << "\n\nLower bound of 22: " 56 << *( intMultiset.lower_bound( 22 ) ); 57 cout << "\nUpper bound of 22: " fig21_19.cpp 58 << *( intMultiset.upper_bound( 22 ) ); (3 of 3) 59 60 // p represents pair of const_iterators 61 std::pair< ims::const_iterator, ims::const_iteratorUse a >pa p;ir object to get the 62 lower and upper bound for 63 // use equal_range to determine lower and upper22 bound. 64 // of 22 in intMultiset 65 p = intMultiset.equal_range( 22 ); 66 67 cout << "\n\nequal_range of 22:" 68 << "\n Lower bound: " << *( p.first ) 69 << "\n Upper bound: " << *( p.second ); 70 71 cout << endl; 72 73 return 0; 74 75 } // end main

Found value 15 fig21_19.cpp Did not find value 20 output (1 of 1)

After insert, intMultiset contains: 1 7 9 13 15 15 18 22 22 30 85 100

Lower bound of 22: 22 Upper bound of 22: 30 equal_range of 22: Lower bound: 22 Upper bound: 30

• set – Header – Implementation identical to multiset – Unique keys • Duplicates ignored and not inserted – Supports bidirectional iterators (but not random access) – std::set< type, std::less > name;

 2003 Prentice Hall, Inc. All rights reserved. 53 1 // Fig. 21.20: fig21_20.cpp Outline 2 // Standard library class set test program. 3 #include 4 fig21_20.cpp 5 using std::cout; (1 of 3) 6 using std::endl; 7 Create set. Syntax similar to 8 #include multiset. 9 10 // define short name for set type used in this program 11 typedef std::set< double, std::less< double > > double_set; 12 13 #include 14 15 int main() 16 { 17 const int SIZE = 5; 18 double a[ SIZE ] = { 2.1, 4.2, 9.5, 2.1, 3.7 }; 19 20 double_set doubleSet( a, a + SIZE ); 21 std::ostream_iterator< double > output( cout, " " ); 22 23 cout << "doubleSet contains: "; 24 std::copy( doubleSet.begin(), doubleSet.end(), output ); 25

 2003 Prentice Hall, Inc. All rights reserved. 54 26 // p represents pair containing const_iterator and bool Outline 27 std::pair< double_set::const_iterator, bool > p; 28 29 // insert 13.8 in doubleSet; insert returns pair in which fig21_20.cpp 30 // p.first represents location of 13.8 in doubleSet and pair object has a bool (2 of 3) 31 // p.second represents whether 13.8 was inserted value representing whether or 32 p = doubleSet.insert( 13.8 ); // value not in set 33 not the item was inserted. 34 cout << "\n\n" << *( p.first ) 35 << ( p.second ? " was" : " was not" ) << " inserted"; 36 37 cout << "\ndoubleSet contains: "; 38 std::copy( doubleSet.begin(), doubleSet.end(), output ); 39 40 // insert 9.5 in doubleSet 41 p = doubleSet.insert( 9.5 ); // value already in set 42 43 cout << "\n\n" << *( p.first ) 44 << ( p.second ? " was" : " was not" ) << " inserted"; 45

 2003 Prentice Hall, Inc. All rights reserved. 55 46 cout << "\ndoubleSet contains: "; Outline 47 std::copy( doubleSet.begin(), doubleSet.end(), output ); 48 49 cout << endl; fig21_20.cpp 50 (3 of 3) 51 return 0; 52 fig21_20.cpp 53 } // end main output (1 of 1) doubleSet contains: 2.1 3.7 4.2 9.5

13.8 was inserted doubleSet contains: 2.1 3.7 4.2 9.5 13.8

9.5 was not inserted doubleSet contains: 2.1 3.7 4.2 9.5 13.8

• multimap – Header – Fast storage and retrieval of keys and associated values • Has key/value pairs – Duplicate keys allowed (multiple values for a single key) • One-to-many relationship • I.e., one student can take many courses – Insert pair objects (with a key and value) – Bidirectional iterators

• Example std::multimap< int, double, std::less< int > > mmapObject; – Key type int – Value type double – Sorted in ascending order • Use typedef to simplify code

typedef std::multimap> mmid; mmid mmapObject; mmapObject.insert( mmid::value_type( 1, 3.4 ) ); – Inserts key 1 with value 3.4 – mmid::value_type creates a pair object

 2003 Prentice Hall, Inc. All rights reserved. 58 1 // Fig. 21.21: fig21_21.cpp Outline 2 // Standard library class multimap test program. 3 #include 4 fig21_21.cpp 5 using std::cout; Definition for a multimap(1 of 2) 6 using std::endl; that maps integer keys to 7 double values. 8 #include // map class-template definition 9 10 // define short name for multimap type used in this program 11 typedef std::multimap< int, double, std::less< int > > mmid; 12 Create multimap and insert 13 int main() key-value pairs. 14 { 15 mmid pairs; 16 17 cout << "There are currently " << pairs.count( 15 ) 18 << " pairs with key 15 in the multimap\n"; 19 20 // insert two value_type objects in pairs 21 pairs.insert( mmid::value_type( 15, 2.7 ) ); 22 pairs.insert( mmid::value_type( 15, 99.3 ) ); 23 24 cout << "After inserts, there are " 25 << pairs.count( 15 ) 26 << " pairs with key 15\n\n";

 2003 Prentice Hall, Inc. All rights reserved. 59 27 Outline 28 // insert five value_type objects in pairs 29 pairs.insert( mmid::value_type( 30, 111.11 ) ); 30 pairs.insert( mmid::value_type( 10, 22.22 ) ); fig21_21.cpp 31 pairs.insert( mmid::value_type( 25, 33.333 ) ); (2 of 2) 32 pairs.insert( mmid::value_type( 20, 9.345 ) ); 33 pairs.insert( mmid::value_type( 5, 77.54 ) ); 34 Use iterator to print entire 35 cout << "Multimap pairs contains:\nKey\tValue\n"; multimap. 36 37 // use const_iterator to walk through elements of pairs 38 for ( mmid::const_iterator iter = pairs.begin(); 39 iter != pairs.end(); ++iter ) 40 cout << iter->first << '\t' 41 << iter->second << '\n'; 42 43 cout << endl; 44 45 return 0; 46 47 } // end main

Multimap pairs contains: fig21_21.cpp Key Value output (1 of 1) 5 77.54 10 22.22 15 2.7 15 99.3 20 9.345 25 33.333 30 111.11

• map – Header – Like multimap, but only unique key/value pairs • One-to-one mapping (duplicates ignored) – Use [] to access values – Example: for map object m m[30] = 4000.21; • Sets the value of key 30 to 4000.21 – If subscript not in map, creates new key/value pair • Type declaration – std::map< int, double, std::less< int > >;

 2003 Prentice Hall, Inc. All rights reserved. 62 1 // Fig. 21.22: fig21_22.cpp Outline 2 // Standard library class map test program. 3 #include 4 fig21_22.cpp 5 using std::cout; (1 of 2) 6 using std::endl; 7 Again, use typedefs to 8 #include // map class-template definitionsimplify declaration. 9 10 // define short name for map type used in this program 11 typedef std::map< int, double, std::less< int > > mid; 12 13 int main() 14 { 15 mid pairs; 16 Duplicate keys ignored. 17 // insert eight value_type objects in pairs 18 pairs.insert( mid::value_type( 15, 2.7 ) ); 19 pairs.insert( mid::value_type( 30, 111.11 ) ); 20 pairs.insert( mid::value_type( 5, 1010.1 ) ); 21 pairs.insert( mid::value_type( 10, 22.22 ) ); 22 pairs.insert( mid::value_type( 25, 33.333 ) ); 23 pairs.insert( mid::value_type( 5, 77.54 ) ); // dupe ignored 24 pairs.insert( mid::value_type( 20, 9.345 ) ); 25 pairs.insert( mid::value_type( 15, 99.3 ) ); // dupe ignored 26

 2003 Prentice Hall, Inc. All rights reserved. 63 27 cout << "pairs contains:\nKey\tValue\n"; Outline 28 29 // use const_iterator to walk through elements of pairs 30 for ( mid::const_iterator iter = pairs.begin(); fig21_22.cpp 31 iter != pairs.end(); ++iter ) (2 of 2) 32 cout << iter->first << '\t' C an u se su b scr ip t operator to 33 << iter->second << '\n'; ad d o r ch an g e k ey-value 34 pairs. 35 // use subscript operator to change value for key 25 36 pairs[ 25 ] = 9999.99; 37 38 // use subscript operator insert value for key 40 39 pairs[ 40 ] = 8765.43; 40 41 cout << "\nAfter subscript operations, pairs contains:" 42 << "\nKey\tValue\n"; 43 44 for ( mid::const_iterator iter2 = pairs.begin(); 45 iter2 != pairs.end(); ++iter2 ) 46 cout << iter2->first << '\t' 47 << iter2->second << '\n'; 48 49 cout << endl; 50 51 return 0; 52 53 } // end main  2003 Prentice Hall, Inc. All rights reserved. 64 pairs contains: Outline Key Value 5 1010.1 10 22.22 fig21_22.cpp 15 2.7 output (1 of 1) 20 9.345 25 33.333 30 111.11

After subscript operations, pairs contains: Key Value 5 1010.1 10 22.22 15 2.7 20 9.345 25 9999.99 30 111.11 40 8765.43

• Container adapters – stack, queue and priority_queue – Not first class containers • Do not support iterators • Do not provide actual data structure – Programmer can select implementation – Member functions push and pop

• stack – Header – Insertions and deletions at one end – Last-in, first-out (LIFO) data structure – Can use vector, list, or deque (default) – Declarations stack > myStack; stack > myOtherStack; stack anotherStack; // default deque • vector, list – Implementation of stack (default deque) – Does not change behavior, just performance (deque and vector fastest)

 2003 Prentice Hall, Inc. All rights reserved. 67 1 // Fig. 21.23: fig21_23.cpp Outline 2 // Standard library adapter stack test program. 3 #include 4 fig21_23.cpp 5 using std::cout; (1 of 3) 6 using std::endl; 7 8 #include // stack adapter definition 9 #include // vector class-template definition 10 #include // list class-template definition 11 12 // popElements function-template prototype 13 template< class T > 14 void popElements( T &stackRef ); 15 Create stacks with various 16 int main() implementations. 17 { 18 // stack with default underlying deque 19 std::stack< int > intDequeStack; 20 21 // stack with underlying vector 22 std::stack< int, std::vector< int > > intVectorStack; 23 24 // stack with underlying list 25 std::stack< int, std::list< int > > intListStack; 26

 2003 Prentice Hall, Inc. All rights reserved. 68 27 // push the values 0-9 onto each stack Outline 28 for ( int i = 0; i < 10; ++i ) { 29 intDequeStack.push( i ); 30 intVectorStack.push( i ); Use member function push.fig21_23.cpp 31 intListStack.push( i ); (2 of 3) 32 33 } // end for 34 35 // display and remove elements from each stack 36 cout << "Popping from intDequeStack: "; 37 popElements( intDequeStack ); 38 cout << "\nPopping from intVectorStack: "; 39 popElements( intVectorStack ); 40 cout << "\nPopping from intListStack: "; 41 popElements( intListStack ); 42 43 cout << endl; 44 45 return 0; 46 47 } // end main 48

 2003 Prentice Hall, Inc. All rights reserved. 69 49 // pop elements from stack object to which stackRef refers Outline 50 template< class T > 51 void popElements( T &stackRef ) 52 { fig21_23.cpp 53 while ( !stackRef.empty() ) { (3 of 3) 54 cout << stackRef.top() << ' '; // view top element 55 stackRef.pop(); // remove top element fig21_23.cpp 56 output (1 of 1) 57 } // end while 58 59 } // end function popElements

Popping from intDequeStack: 9 8 7 6 5 4 3 2 1 0 Popping from intVectorStack: 9 8 7 6 5 4 3 2 1 0 Popping from intListStack: 9 8 7 6 5 4 3 2 1 0

• queue – Header – Insertions at back, deletions at front – First-in-first-out (FIFO) data structure – Implemented with list or deque (default) • std::queue values; • Functions – push( element ) • Same as push_back, add to end – pop( element ) • Implemented with pop_front, remove from front – empty() – size()

 2003 Prentice Hall, Inc. All rights reserved. 71 1 // Fig. 21.24: fig21_24.cpp Outline 2 // Standard library adapter queue test program. 3 #include 4 fig21_24.cpp 5 using std::cout; (1 of 2) 6 using std::endl; 7 8 #include // queue adapter definitionCreate queue, add values 9 using push. 10 int main() 11 { 12 std::queue< double > values; 13 14 // push elements onto queue values 15 values.push( 3.2 ); 16 values.push( 9.8 ); 17 values.push( 5.4 ); 18 19 cout << "Popping from values: "; 20 21 while ( !values.empty() ) { 22 cout << values.front() << ' '; // view front element 23 values.pop(); // remove element 24 25 } // end while 26

Popping from values: 3.2 9.8 5.4 fig21_24.cpp output (1 of 1)

• priority_queue – Header – Insertions happen in sorted order, deletions from front – Implemented with vector (default) or deque – Highest priority element always removed first • Heapsort algorithm puts largest elements at front • less default, programmer can specify other comparator – Functions • push(value), pop(value) • top() – View top element • size() • empty()

 2003 Prentice Hall, Inc. All rights reserved. 74 1 // Fig. 21.25: fig21_25.cpp Outline 2 // Standard library adapter priority_queue test program. 3 #include 4 fig21_25.cpp 5 using std::cout; (1 of 2) 6 using std::endl; 7 8 #include // priority_queue adapter definitionCreate priority queue. 9 10 int main() 11 { 12 std::priority_queue< double > priorities; 13 Insert items using push. When 14 // push elements onto priorities using pop, highest priority 15 priorities.push( 3.2 ); (largest) items removed first. 16 priorities.push( 9.8 ); 17 priorities.push( 5.4 ); 18 19 cout << "Popping from priorities: "; 20 21 while ( !priorities.empty() ) { 22 cout << priorities.top() << ' '; // view top element 23 priorities.pop(); // remove top element 24 25 } // end while 26

• Before STL – Class libraries incompatible among vendors – Algorithms built into container classes • STL separates containers and algorithms – Easier to add new algorithms – More efficient, avoids virtual function calls –

• Functions to change containers – fill(iterator1, iterator2, value); • Sets range of elements to value – fill_n(iterator1, n, value); • Sets n elements to value, starting at iterator1 – generate(iterator1, iterator2, function); • Like fill, but calls function to set each value – generate(iterator1, quantity, function) • Like fill_n, ""

 2003 Prentice Hall, Inc. All rights reserved. 78 1 // Fig. 21.26: fig21_26.cpp Outline 2 // Standard library algorithms fill, fill_n, generate 3 // and generate_n. 4 #include fig21_26.cpp 5 (1 of 3) 6 using std::cout; 7 using std::endl; 8 9 #include // algorithm definitions 10 #include // vector class-template definition 11 12 char nextLetter(); // prototype Create vector of chars, to 13 be used with various 14 int main() functions. 15 { 16 std::vector< char > chars( 10 ); Function fill. 17 std::ostream_iterator< char > output( cout, " " ); 18 19 // fill chars with 5s 20 std::fill( chars.begin(), chars.end(), '5' ); 21 22 cout << "Vector chars after filling with 5s:\n"; 23 std::copy( chars.begin(), chars.end(), output ); 24

 2003 Prentice Hall, Inc. All rights reserved. 79 25 // fill first five elements of chars with As Outline 26 std::fill_n( chars.begin(), 5, 'A' ); 27 28 cout << "\n\nVector chars after filling five elements" fig21_26.cpp 29 << " with As:\n"; Function(s2 generate of 3) and 30 std::copy( chars.begin(), chars.end(), output ); generate_n use function 31 nextLetter. 32 // generate values for all elements of chars with nextLetter 33 std::generate( chars.begin(), chars.end(), nextLetter ); 34 35 cout << "\n\nVector chars after generating letters A-J:\n"; 36 std::copy( chars.begin(), chars.end(), output ); 37 38 // generate values for first five elements of chars 39 // with nextLetter 40 std::generate_n( chars.begin(), 5, nextLetter ); 41 42 cout << "\n\nVector chars after generating K-O for the" 43 << " first five elements:\n"; 44 std::copy( chars.begin(), chars.end(), output ); 45 46 cout << endl; 47 48 return 0; 49 50 } // end main

 2003 Prentice Hall, Inc. All rights reserved. 80 51 Outline 52 // returns next letter in the alphabet (starts with A) 53 char nextLetter() 54 { fig21_26.cpp 55 static char letter = 'A'; (3 of 3) 56 return letter++; 57 fig21_26.cpp 58 } // end function nextLetter output (1 of 1) Vector chars after filling with 5s: 5 5 5 5 5 5 5 5 5 5

Vector chars after filling five elements with As: A A A A A 5 5 5 5 5

Vector chars after generating letters A-J: A B C D E F G H I J

Vector chars after generating K-O for the first five elements: K L M N O F G H I J

 2003 Prentice Hall, Inc. All rights reserved. 81 21.5.2 equal, mismatch and lexicographical_compare • Functions to compare sequences of values – equal • Returns true if sequences are equal (uses ==) • Can return false if of unequal length equal(iterator1, iterator2, iterator3); • Compares sequence from iterator1 to iterator2 with sequence beginning at iterator3 – mismatch • Arguments same as equal • Returns a pair object with iterators pointing to mismatch – If no mismatch, pair iterators equal to last item pair < iterator, iterator > myPairObject; myPairObject = mismatch( iter1, iter2, iter3);

 2003 Prentice Hall, Inc. All rights reserved. 82 21.5.2 equal, mismatch and lexicographical_compare • Functions to compare sequences of values – lexicographical_compare • Compare contents of two character arrays • Returns true if element in first sequence smaller than corresponding element in second

bool result = lexicographical_compare(iter1, iter2, iter3);

 2003 Prentice Hall, Inc. All rights reserved. 83 1 // Fig. 21.27: fig21_27.cpp Outline 2 // Standard library functions equal, 3 // mismatch and lexicographical_compare. 4 #include fig21_27.cpp 5 (1 of 3) 6 using std::cout; 7 using std::endl; 8 9 #include // algorithm definitions 10 #include // vector class-template definition 11 12 int main() 13 { 14 const int SIZE = 10; 15 int a1[ SIZE ] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; 16 int a2[ SIZE ] = { 1, 2, 3, 4, 1000, 6, 7, 8, 9, 10 }; 17 18 std::vector< int > v1( a1, a1 + SIZE ); 19 std::vector< int > v2( a1, a1 + SIZE ); 20 std::vector< int > v3( a2, a2 + SIZE ); 21 22 std::ostream_iterator< int > output( cout, " " ); 23

 2003 Prentice Hall, Inc. All rights reserved. 84 24 cout << "Vector v1 contains: "; Outline 25 std::copy( v1.begin(), v1.end(), output ); 26 cout << "\nVector v2 contains: "; 27 std::copy( v2.begin(), v2.end(), output ); fig21_27.cpp 28 cout << "\nVector v3 contains: "; (2 of 3) 29 std::copy( v3.begin(), v3.end(), output ); Use function equal. 30 Compares all of v1 with v2. 31 // compare vectors v1 and v2 for equality 32 bool result = 33 std::equal( v1.begin(), v1.end(), v2.begin() ); 34 35 cout << "\n\nVector v1 " << ( result ? "is" : "is not" ) 36 << " equal to vector v2.\n"; 37 38 // compare vectors v1 and v3 for equality 39 result = std::equal( v1.begin(), v1.end(), v3.begin() ); 40 cout << "Vector v1 " << ( result ? "is" : "is not" ) 41 << " equal to vector v3.\n"; 42 43 // location represents pair of vector iterators 44 std::pair< std::vector< int >::iterator, Note use of function 45 std::vector< int >::iterator > location; mismatch. 46 47 // check for mismatch between v1 and v3 48 location = 49 std::mismatch( v1.begin(), v1.end(), v3.begin() ); 50  2003 Prentice Hall, Inc. All rights reserved. 85 51 cout << "\nThere is a mismatch between v1 and v3 at " Outline 52 << "location " << ( location.first - v1.begin() ) 53 << "\nwhere v1 contains " << *location.first 54 << " and v3 contains " << *location.second fig21_27.cpp 55 << "\n\n"; (3 of 3) 56 57 char c1[ SIZE ] = "HELLO"; Use lexicographical_compare. 58 char c2[ SIZE ] = "BYE BYE"; 59 60 // perform lexicographical comparison of c1 and c2 61 result = std::lexicographical_compare( 62 c1, c1 + SIZE, c2, c2 + SIZE ); 63 64 cout << c1 65 << ( result ? " is less than " : 66 " is greater than or equal to " ) 67 << c2 << endl; 68 69 return 0; 70 71 } // end main

 2003 Prentice Hall, Inc. All rights reserved. 86 Vector v1 contains: 1 2 3 4 5 6 7 8 9 10 Outline Vector v2 contains: 1 2 3 4 5 6 7 8 9 10 Vector v3 contains: 1 2 3 4 1000 6 7 8 9 10 fig21_27.cpp Vector v1 is equal to vector v2. output (1 of 1) Vector v1 is not equal to vector v3.

There is a mismatch between v1 and v3 at location 4 where v1 contains 5 and v3 contains 1000

HELLO is greater than or equal to BYE BYE

 2003 Prentice Hall, Inc. All rights reserved. 87 21.5.3 remove, remove_if, remove_copy and remove_copy_if • remove – remove( iter1, iter2, value); – Removes all instances of value in range (iter1-iter2) • Moves instances of value towards end • Does not change size of container or delete elements – Returns iterator to "new" end of container – Elements after new iterator are undefined (0) • remove_copy – Copies one vector to another while removing an element – remove_copy(iter1, iter2, iter3, value); • Copies elements not equal to value into iter3 (output iterator) • Uses range iter1-iter2

 2003 Prentice Hall, Inc. All rights reserved. 88 21.5.3 remove, remove_if, remove_copy and remove_copy_if • remove_if – Like remove • Returns iterator to last element • Removes elements that return true for specified function remove_if(iter1,iter2, function); • Elements passed to function, which returns a bool • remove_copy_if – Like remove_copy and remove_if – Copies range of elements to iter3, except those for which function returns true remove_copy_if(iter1, iter2, iter3, function);

 2003 Prentice Hall, Inc. All rights reserved. 89 1 // Fig. 21.28: fig21_28.cpp Outline 2 // Standard library functions remove, remove_if, 3 // remove_copy and remove_copy_if. 4 #include fig21_28.cpp 5 (1 of 4) 6 using std::cout; 7 using std::endl; 8 9 #include // algorithm definitions 10 #include // vector class-template definition 11 12 bool greater9( int ); // prototype 13 14 int main() 15 { 16 const int SIZE = 10; 17 int a[ SIZE ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 }; 18 19 std::ostream_iterator< int > output( cout, " " ); 20 21 std::vector< int > v( a, a + SIZE ); 22 std::vector< int >::iterator newLastElement; 23 24 cout << "Vector v before removing all 10s:\n "; 25 std::copy( v.begin(), v.end(), output ); 26

 2003 Prentice Hall, Inc. All rights reserved. 90 27 // remove 10 from v Outline 28 newLastElement = std::remove( v.begin(), v.end(), 10 ); 29 30 cout << "\nVector v after removing all 10s:\n "; Remove all 1fig0's2 f1r_o2m8 .vcpp. 31 std::copy( v.begin(), newLastElement, output ); Returns an iter(2ato ofr 4 p)ointing to 32 the new last element. 33 std::vector< int > v2( a, a + SIZE ); 34 std::vector< int > c( SIZE, 0 ); 35 36 cout << "\n\nVector v2 before removing all 10s " 37 << "and copying:\n "; Use remove_copy to create 38 std::copy( v2.begin(), v2.end(), output ); a duplicate of v, with all the 39 10's removed. 40 // copy from v2 to c, removing 10s in the process 41 std::remove_copy( v2.begin(), v2.end(), c.begin(), 10 ); 42 43 cout << "\nVector c after removing all 10s from v2:\n "; 44 std::copy( c.begin(), c.end(), output ); 45 46 std::vector< int > v3( a, a + SIZE ); 47 48 cout << "\n\nVector v3 before removing all elements" 49 << "\ngreater than 9:\n "; 50 std::copy( v3.begin(), v3.end(), output ); 51

 2003 Prentice Hall, Inc. All rights reserved. 91 52 // remove elements greater than 9 from v3 Outline 53 newLastElement = 54 std::remove_if( v3.begin(), v3.end(), greater9 ); 55 fig21_28.cpp 56 cout << "\nVector v3 after removing all elements" Use function greater9(3 of 4) to 57 << "\ngreater than 9:\n "; determine whether to remove 58 std::copy( v3.begin(), newLastElement, output ); the element. 59 60 std::vector< int > v4( a, a + SIZE ); 61 std::vector< int > c2( SIZE, 0 ); 62 63 cout << "\n\nVector v4 before removing all elements" 64 << "\ngreater than 9 and copying:\n "; 65 std::copy( v4.begin(), v4.end(), outputNo );te use of remove_copy_if. 66 67 // copy elements from v4 to c2, removing elements greater 68 // than 9 in the process 69 std::remove_copy_if( 70 v4.begin(), v4.end(), c2.begin(), greater9 ); 71 72 cout << "\nVector c2 after removing all elements" 73 << "\ngreater than 9 from v4:\n "; 74 std::copy( c2.begin(), c2.end(), output ); 75

 2003 Prentice Hall, Inc. All rights reserved. 92 76 cout << endl; Outline 77 78 return 0; 79 fig21_28.cpp 80 } // end main (4 of 4) 81 82 // determine whether argument is greater than 9 83 bool greater9( int x ) 84 { 85 return x > 9; 86 87 } // end greater9

 2003 Prentice Hall, Inc. All rights reserved. 93 Vector v before removing all 10s: Outline 10 2 10 4 16 6 14 8 12 10 Vector v after removing all 10s: 2 4 16 6 14 8 12 fig21_28.cpp output (1 of 1) Vector v2 before removing all 10s and copying: 10 2 10 4 16 6 14 8 12 10 Vector c after removing all 10s from v2: 2 4 16 6 14 8 12 0 0 0

Vector v3 before removing all elements greater than 9: 10 2 10 4 16 6 14 8 12 10 Vector v3 after removing all elements greater than 9: 2 4 6 8

Vector v4 before removing all elements greater than 9 and copying: 10 2 10 4 16 6 14 8 12 10 Vector c2 after removing all elements greater than 9 from v4: 2 4 6 8 0 0 0 0 0 0

 2003 Prentice Hall, Inc. All rights reserved. 94 21.5.4 replace, replace_if, replace_copy and replace_copy_if • Functions – replace( iter1, iter2, value, newvalue ); • Like remove, except replaces value with newvalue – replace_if( iter1, iter2, function, newvalue ); • Replaces value if function returns true – replace_copy(iter1, iter2, iter3, value, newvalue); • Replaces and copies elements to iter3 • Does not affect originals – replace_copy_if( iter1, iter2, iter3, function, newvalue ); • Replaces and copies elements to iter3 if function returns true

 2003 Prentice Hall, Inc. All rights reserved. 95 1 // Fig. 21.29: fig21_29.cpp Outline 2 // Standard library functions replace, replace_if, 3 // replace_copy and replace_copy_if. 4 #include fig21_29.cpp 5 (1 of 4) 6 using std::cout; 7 using std::endl; 8 9 #include 10 #include 11 12 bool greater9( int ); 13 14 int main() 15 { 16 const int SIZE = 10; 17 int a[ SIZE ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 }; 18 19 std::ostream_iterator< int > output( cout, " " ); 20 21 std::vector< int > v1( a, a + SIZE ); 22 cout << "Vector v1 before replacing all 10s:\n "; 23 std::copy( v1.begin(), v1.end(), output ); 24

 2003 Prentice Hall, Inc. All rights reserved. 96 25 // replace 10s in v1 with 100 Use functions Outline, 26 std::replace( v1.begin(), v1.end(), 10, 100 ); replace 27 replace_copy. 28 cout << "\nVector v1 after replacing 10s with 100s:\n "; fig21_29.cpp 29 std::copy( v1.begin(), v1.end(), output ); (2 of 4) 30 31 std::vector< int > v2( a, a + SIZE ); 32 std::vector< int > c1( SIZE ); 33 34 cout << "\n\nVector v2 before replacing all 10s " 35 << "and copying:\n "; 36 std::copy( v2.begin(), v2.end(), output ); 37 38 // copy from v2 to c1, replacing 10s with 100s 39 std::replace_copy( 40 v2.begin(), v2.end(), c1.begin(), 10, 100 ); 41 42 cout << "\nVector c1 after replacing all 10s in v2:\n "; 43 std::copy( c1.begin(), c1.end(), output ); 44 45 std::vector< int > v3( a, a + SIZE ); 46 47 cout << "\n\nVector v3 before replacing values greater" 48 << " than 9:\n "; 49 std::copy( v3.begin(), v3.end(), output ); 50

 2003 Prentice Hall, Inc. All rights reserved. 97 51 // replace values greater than 9 in v3 with 100 Outline 52 std::replace_if( v3.begin(), v3.end(), greater9, 100 ); 53 54 cout << "\nVector v3 after replacing all values greater" 55 << "\nthan 9 with 100s:\n "; fig21_29.cpp 56 std::copy( v3.begin(), v3.end(), output ); (3 of 4) 57 58 std::vector< int > v4( a, a + SIZE ); 59 std::vector< int > c2( SIZE ); 60 61 cout << "\n\nVector v4 before replacing all values greater " 62 << "than 9 and copying:\n "; 63 std::copy( v4.begin(), v4.end(), output ); 64 65 // copy v4 to c2, replacing elements greater than 9 with 100 66 std::replace_copy_if( 67 v4.begin(), v4.end(), c2.begin(), greater9, 100 ); 68 69 cout << "\nVector c2 after replacing all values greater " 70 << "than 9 in v4:\n "; 71 std::copy( c2.begin(), c2.end(), output ); 72 73 cout << endl; 74 75 return 0; 76 77 } // end main  2003 Prentice Hall, Inc. All rights reserved. 98 78 Outline 79 // determine whether argument is greater than 9 80 bool greater9( int x ) 81 { 82 return x > 9; fig21_29.cpp 83 (4 of 4) 84 } // end function greater9

Vector v1 before replacing all 10s: fig21_29.cpp 10 2 10 4 16 6 14 8 12 10 output (1 of 1) Vector v1 after replacing 10s with 100s: 100 2 100 4 16 6 14 8 12 100

Vector v2 before replacing all 10s and copying: 10 2 10 4 16 6 14 8 12 10 Vector c1 after replacing all 10s in v2: 100 2 100 4 16 6 14 8 12 100

Vector v3 before replacing values greater than 9: 10 2 10 4 16 6 14 8 12 10 Vector v3 after replacing all values greater than 9 with 100s: 100 2 100 4 100 6 100 8 100 100

Vector v4 before replacing all values greater than 9 and copying: 10 2 10 4 16 6 14 8 12 10 Vector c2 after replacing all values greater than 9 in v4: 100 2 100 4 100 6 100 8 100 100  2003 Prentice Hall, Inc. All rights reserved. 99 21.5.5 Mathematical Algorithms

• random_shuffle(iter1, iter2) – Randomly mixes elements in range • count(iter1, iter2, value) – Returns number of instances of value in range • count_if(iter1, iter2, function) – Counts number of instances that return true • min_element(iter1, iter2) – Returns iterator to smallest element • max_element(iter1, iter2) – Returns iterator to largest element

• accumulate(iter1, iter2) – Returns sum of elements in range • for_each(iter1, iter2, function) – Calls function on every element in range – Does not modify element • transform(iter1, iter2, iter3, function) – Calls function for all elements in range of iter1-iter2, copies result to iter3

 2003 Prentice Hall, Inc. All rights reserved. 101 1 // Fig. 21.30: fig21_30.cpp Outline 2 // Mathematical algorithms of the standard library. 3 #include 4 fig21_30.cpp 5 using std::cout; (1 of 5) 6 using std::endl; 7 8 #include // algorithm definitions 9 #include // accumulate is defined here 10 #include 11 12 bool greater9( int ); 13 void outputSquare( int ); 14 int calculateCube( int ); 15 16 int main() 17 { 18 const int SIZE = 10; 19 int a1[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; 20 21 std::vector< int > v( a1, a1 + SIZE ); 22 std::ostream_iterator< int > output( cout, " " ); 23 24 cout << "Vector v before random_shuffle: "; 25 std::copy( v.begin(), v.end(), output ); 26

 2003 Prentice Hall, Inc. All rights reserved. 102 27 // shuffle elements of v Outline 28 std::random_shuffle( v.begin(), v.end() ); 29 30 cout << "\nVector v after random_shuffle: "; fig21_30.cpp 31 std::copy( v.begin(), v.end(), output ); (2 of 5) 32 33 int a2[] = { 100, 2, 8, 1, 50, 3, 8, 8, 9, 10 }; 34 std::vector< int > v2( a2, a2 + SIZE ); 35 36 cout << "\n\nVector v2 contains: "; 37 std::copy( v2.begin(), v2.end(), output ); 38 39 // count number of elements in v2 with value 8 40 int result = std::count( v2.begin(), v2.end(), 8 ); 41 42 std::cout << "\nNumber of elements matching 8: " << result; 43 44 // count number of elements in v2 that are greater than 9 45 result = std::count_if( v2.begin(), v2.end(), greater9 ); 46 47 cout << "\nNumber of elements greater than 9: " << result; 48

 2003 Prentice Hall, Inc. All rights reserved. 103 49 // locate minimum element in v2 Outline 50 cout << "\n\nMinimum element in Vector v2 is: " 51 << *( std::min_element( v2.begin(), v2.end() ) ); 52 fig21_30.cpp 53 // locate maximum element in v2 (3 of 5) 54 cout << "\nMaximum element in Vector v2 is: " 55 << *( std::max_element( v2.begin(), v2.end() ) ); 56 57 // calculate sum of elements in v 58 cout << "\n\nThe total of the elements in Vector v is: " 59 << std::accumulate( v.begin(), v.end(), 0 ); 60 61 cout << "\n\nThe square of every integer in Vector v is:\n"; 62 63 // output square of every element in v 64 std::for_each( v.begin(), v.end(), outputSquare ); 65 66 std::vector< int > cubes( SIZE ); 67 68 // calculate cube of each element in v; 69 // place results in cubes 70 std::transform( 71 v.begin(), v.end(), cubes.begin(), calculateCube );

 2003 Prentice Hall, Inc. All rights reserved. 104 72 Outline 73 cout << "\n\nThe cube of every integer in Vector v is:\n"; 74 std::copy( cubes.begin(), cubes.end(), output ); 75 fig21_30.cpp 76 cout << endl; (4 of 5) 77 78 return 0; 79 80 } // end main 81 82 // determine whether argument is greater than 9 83 bool greater9( int value ) 84 { 85 return value > 9; 86 87 } // end function greater9 88 89 // output square of argument 90 void outputSquare( int value ) 91 { 92 cout << value * value << ' '; 93 94 } // end function outputSquare 95

 2003 Prentice Hall, Inc. All rights reserved. 105 96 // return cube of argument Outline 97 int calculateCube( int value ) 98 { 99 return value * value * value; fig21_30.cpp 100 (5 of 5) 101 } // end function calculateCube

Vector v before random_shuffle: 1 2 3 4 5 6 7 8 9 10 fig21_30.cpp Vector v after random_shuffle: 5 4 1 3 7 8 9 10 6 2 output (1 of 1)

Vector v2 contains: 100 2 8 1 50 3 8 8 9 10 Number of elements matching 8: 3 Number of elements greater than 9: 3

Minimum element in Vector v2 is: 1 Maximum element in Vector v2 is: 100

The total of the elements in Vector v is: 55

The square of every integer in Vector v is: 25 16 1 9 49 64 81 100 36 4

The cube of every integer in Vector v is: 125 64 1 27 343 512 729 1000 216 8

• find(iter1, iter2, value) – Returns iterator to first instance of value (in range) • find_if(iter1, iter2, function) – Like find – Returns iterator when function returns true • sort(iter1, iter2) – Sorts elements in ascending order • binary_search(iter1, iter2, value) – Searches ascending sorted list for value – Uses binary search

 2003 Prentice Hall, Inc. All rights reserved. 107 1 // Fig. 21.31: fig21_31.cpp Outline 2 // Standard library search and sort algorithms. 3 #include 4 fig21_31.cpp 5 using std::cout; (1 of 4) 6 using std::endl; 7 8 #include // algorithm definitions 9 #include // vector class-template definition 10 11 bool greater10( int value ); // prototype 12 13 int main() 14 { 15 const int SIZE = 10; 16 int a[ SIZE ] = { 10, 2, 17, 5, 16, 8, 13, 11, 20, 7 }; 17 18 std::vector< int > v( a, a + SIZE ); 19 std::ostream_iterator< int > output( cout, " " ); 20 21 cout << "Vector v contains: "; 22 std::copy( v.begin(), v.end(), output ); 23 24 // locate first occurrence of 16 in v 25 std::vector< int >::iterator location; 26 location = std::find( v.begin(), v.end(), 16 );

 2003 Prentice Hall, Inc. All rights reserved. 108 27 Outline 28 if ( location != v.end() ) 29 cout << "\n\nFound 16 at location " 30 << ( location - v.begin() ); fig21_31.cpp 31 else (2 of 4) 32 cout << "\n\n16 not found"; 33 34 // locate first occurrence of 100 in v 35 location = std::find( v.begin(), v.end(), 100 ); 36 37 if ( location != v.end() ) 38 cout << "\nFound 100 at location " 39 << ( location - v.begin() ); 40 else 41 cout << "\n100 not found"; 42 43 // locate first occurrence of value greater than 10 in v 44 location = std::find_if( v.begin(), v.end(), greater10 ); 45 46 if ( location != v.end() ) 47 cout << "\n\nThe first value greater than 10 is " 48 << *location << "\nfound at location " 49 << ( location - v.begin() ); 50 else 51 cout << "\n\nNo values greater than 10 were found"; 52

 2003 Prentice Hall, Inc. All rights reserved. 109 53 // sort elements of v Outline 54 std::sort( v.begin(), v.end() ); 55 56 cout << "\n\nVector v after sort: "; fig21_31.cpp 57 std::copy( v.begin(), v.end(), output ); (3 of 4) 58 59 // use binary_search to locate 13 in v 60 if ( std::binary_search( v.begin(), v.end(), 13 ) ) 61 cout << "\n\n13 was found in v"; 62 else 63 cout << "\n\n13 was not found in v"; 64 65 // use binary_search to locate 100 in v 66 if ( std::binary_search( v.begin(), v.end(), 100 ) ) 67 cout << "\n100 was found in v"; 68 else 69 cout << "\n100 was not found in v"; 70 71 cout << endl; 72 73 return 0; 74 75 } // end main 76

 2003 Prentice Hall, Inc. All rights reserved. 110 77 // determine whether argument is greater than 10 Outline 78 bool greater10( int value ) 79 { 80 return value > 10; fig21_31.cpp 81 (4 of 4) 82 } // end function greater10

Vector v contains: 10 2 17 5 16 8 13 11 20 7 fig21_31.cpp output (1 of 1) Found 16 at location 4 100 not found

The first value greater than 10 is 17 found at location 2

Vector v after sort: 2 5 7 8 10 11 13 16 17 20

13 was found in v 100 was not found in v

• swap(element1, element2) – Exchanges two values – swap( a[ 0 ], a[ 1 ] );

• iter_swap(iter1, iter2) – Exchanges the values to which the iterators refer

• swap_ranges(iter1, iter2, iter3) – Swap the elements from iter1-iter2 with elements beginning at iter3

 2003 Prentice Hall, Inc. All rights reserved. 112 1 // Fig. 21.32: fig21_32.cpp Outline 2 // Standard library algorithms iter_swap, swap and swap_ranges. 3 #include 4 fig21_32.cpp 5 using std::cout; (1 of 2) 6 using std::endl; 7 8 #include // algorithm definitions 9 10 int main() 11 { 12 const int SIZE = 10; 13 int a[ SIZE ] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; 14 std::ostream_iterator< int > output( cout, " " ); 15 16 cout << "Array a contains:\n "; 17 std::copy( a, a + SIZE, output ); 18 19 // swap elements at locations 0 and 1 of array a 20 std::swap( a[ 0 ], a[ 1 ] ); 21 22 cout << "\nArray a after swapping a[0] and a[1] " 23 << "using swap:\n "; 24 std::copy( a, a + SIZE, output ); 25

 2003 Prentice Hall, Inc. All rights reserved. 113 26 // use iterators to swap elements at locations Outline 27 // 0 and 1 of array a 28 std::iter_swap( &a[ 0 ], &a[ 1 ] ); 29 cout << "\nArray a after swapping a[0] and a[1] " fig21_32.cpp 30 << "using iter_swap:\n "; (2 of 2) 31 std::copy( a, a + SIZE, output ); 32 33 // swap elements in first five elements of array a with 34 // elements in last five elements of array a 35 std::swap_ranges( a, a + 5, a + 5 ); 36 37 cout << "\nArray a after swapping the first five elements\n" 38 << "with the last five elements:\n "; 39 std::copy( a, a + SIZE, output ); 40 41 cout << endl; 42 43 return 0; 44 45 } // end main

 2003 Prentice Hall, Inc. All rights reserved. 114 Array a contains: Outline 1 2 3 4 5 6 7 8 9 10 Array a after swapping a[0] and a[1] using swap: 2 1 3 4 5 6 7 8 9 10 fig21_32.cpp Array a after swapping a[0] and a[1] using iter_swap: output (1 of 1) 1 2 3 4 5 6 7 8 9 10 Array a after swapping the first five elements with the last five elements: 6 7 8 9 10 1 2 3 4 5

• copy_backward(iter1, iter2, iter3) – Copy elements from iter1-iter2 to iter3, in reverse order • merge(iter1, iter2, iter3, iter4, iter5) – Ranges iter1-iter2 and iter3-iter4 must be sorted in ascending order – merge copies both lists into iter5, in ascending order • unique(iter1, iter2) – Removes duplicate elements from a sorted list – Returns iterator to new end of sequence • reverse(iter1, iter2) – Reverses elements from iter1-iter2

 2003 Prentice Hall, Inc. All rights reserved. 116 1 // Fig. 21.33: fig21_33.cpp Outline 2 // Standard library functions copy_backward, merge, 3 // unique and reverse. 4 #include fig21_33.cpp 5 (1 of 3) 6 using std::cout; 7 using std::endl; 8 9 #include // algorithm definitions 10 #include // vector class-template definition 11 12 int main() 13 { 14 const int SIZE = 5; 15 int a1[ SIZE ] = { 1, 3, 5, 7, 9 }; 16 int a2[ SIZE ] = { 2, 4, 5, 7, 9 }; 17 18 std::vector< int > v1( a1, a1 + SIZE ); 19 std::vector< int > v2( a2, a2 + SIZE ); 20 21 std::ostream_iterator< int > output( cout, " " ); 22 23 cout << "Vector v1 contains: "; 24 std::copy( v1.begin(), v1.end(), output ); 25 cout << "\nVector v2 contains: "; 26 std::copy( v2.begin(), v2.end(), output );

 2003 Prentice Hall, Inc. All rights reserved. 117 27 Outline 28 std::vector< int > results( v1.size() ); 29 30 // place elements of v1 into results in reverse order fig21_33.cpp 31 std::copy_backward( v1.begin(), v1.end(), results.end() ); (2 of 3) 32 33 cout << "\n\nAfter copy_backward, results contains: "; 34 std::copy( results.begin(), results.end(), output ); 35 36 std::vector< int > results2( v1.size() + v2.size() ); 37 38 // merge elements of v1 and v2 into results2 in sorted order 39 std::merge( v1.begin(), v1.end(), v2.begin(), v2.end(), 40 results2.begin() ); 41 42 cout << "\n\nAfter merge of v1 and v2 results2 contains:\n"; 43 std::copy( results2.begin(), results2.end(), output ); 44 45 // eliminate duplicate values from results2 46 std::vector< int >::iterator endLocation; 47 endLocation = 48 std::unique( results2.begin(), results2.end() ); 49 50 cout << "\n\nAfter unique results2 contains:\n"; 51 std::copy( results2.begin(), endLocation, output ); 52

 2003 Prentice Hall, Inc. All rights reserved. 118 53 cout << "\n\nVector v1 after reverse: "; Outline 54 55 // reverse elements of v1 56 std::reverse( v1.begin(), v1.end() ); 57 fig21_33.cpp 58 std::copy( v1.begin(), v1.end(), output ); (3 of 3) 59 60 cout << endl; fig21_33.cpp 61 output (1 of 1) 62 return 0; 63 64 } // end main Vector v1 contains: 1 3 5 7 9 Vector v2 contains: 2 4 5 7 9

After copy_backward, results contains: 1 3 5 7 9

After merge of v1 and v2 results2 contains: 1 2 3 4 5 5 7 7 9 9

After unique results2 contains: 1 2 3 4 5 7 9

Vector v1 after reverse: 9 7 5 3 1

• inplace_merge(iter1, iter2, iter3) – Merges two sorted sequences (iter1-iter2, iter2-iter3) inside the same container

• unique_copy(iter1, iter2, iter3) – Copies all unique elements in sorted array (from iter1-iter2) into iter3

• reverse_copy(iter1, iter2, iter3) – Reverses elements in iter1-iter2, copies into iter3

 2003 Prentice Hall, Inc. All rights reserved. 120 1 // Fig. 21.34: fig21_34.cpp Outline 2 // Standard library algorithms inplace_merge, 3 // reverse_copy and unique_copy. 4 #include fig21_34.cpp 5 (1 of 2) 6 using std::cout; 7 using std::endl; 8 9 #include // algorithm definitions 10 #include // vector class-template definition 11 #include // back_inserter definition 12 13 int main() 14 { 15 const int SIZE = 10; 16 int a1[ SIZE ] = { 1, 3, 5, 7, 9, 1, 3, 5, 7, 9 }; 17 std::vector< int > v1( a1, a1 + SIZE ); 18 19 std::ostream_iterator< int > output( cout, " " ); 20 21 cout << "Vector v1 contains: "; 22 std::copy( v1.begin(), v1.end(), output ); 23 24 // merge first half of v1 with second half of v1 such that 25 // v1 contains sorted set of elements after merge 26 std::inplace_merge( v1.begin(), v1.begin() + 5, v1.end() ); 27  2003 Prentice Hall, Inc. All rights reserved. 121 28 cout << "\nAfter inplace_merge, v1 contains: "; Outline 29 std::copy( v1.begin(), v1.end(), output ); 30 31 std::vector< int > results1; fig21_34.cpp 32 (2 of 2) 33 // copy only unique elements of v1 into results1 34 std::unique_copy( 35 v1.begin(), v1.end(), std::back_inserter( results1 ) ); 36 37 cout << "\nAfter unique_copy results1 contains: "; 38 std::copy( results1.begin(), results1.end(), output ); 39 40 std::vector< int > results2; 41 42 cout << "\nAfter reverse_copy, results2 contains: "; 43 44 // copy elements of v1 into results2 in reverse order 45 std::reverse_copy( 46 v1.begin(), v1.end(), std::back_inserter( results2 ) ); 47 48 std::copy( results2.begin(), results2.end(), output ); 49 50 cout << endl; 51 52 return 0; 53 54 } // end main  2003 Prentice Hall, Inc. All rights reserved. 122 Vector v1 contains: 1 3 5 7 9 1 3 5 7 9 Outline After inplace_merge, v1 contains: 1 1 3 3 5 5 7 7 9 9 After unique_copy results1 contains: 1 3 5 7 9 After reverse_copy, results2 contains: 9 9 7 7 5 5 3 3 1 1 fig21_34.cpp output (1 of 1)

• includes(iter1, iter2, iter3, iter4) – Returns true if iter1-iter2 contains iter3-iter4 – Both ranges must be sorted a1: 1 2 3 4 a2: 1 3 a1 includes a3 • set_difference(iter1, iter2, iter3, iter4, iter5) – Copies elements in first set (1-2) that are not in second set (3-4) into iter5 • set_intersection(iter1, iter2, iter3, iter4, iter5) – Copies common elements from the two sets (1-2, 3-4) into iter5

• set_symmetric_difference(iter1, iter2, iter3, iter4, iter5) – Copies elements in set (1-2) but not set (3-4), and vice versa, into iter5 • a1: 1 2 3 4 5 6 7 8 9 10 • a2: 4 5 6 7 8 • set_symmetric_difference: 1 2 3 9 10 – Both sets must be sorted

• set_union( iter1, iter2, iter3, iter4, iter5) – Copies elements in either or both sets to iter5 – Both sets must be sorted

 2003 Prentice Hall, Inc. All rights reserved. 125 1 // Fig. 21.35: fig21_35.cpp Outline 2 // Standard library algorithms includes, set_difference, 3 // set_intersection, set_symmetric_difference and set_union. 4 #include fig21_35.cpp 5 (1 of 3) 6 using std::cout; 7 using std::endl; 8 9 #include // algorithm definitions 10 11 int main() 12 { 13 const int SIZE1 = 10, SIZE2 = 5, SIZE3 = 20; 14 int a1[ SIZE1 ] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; 15 int a2[ SIZE2 ] = { 4, 5, 6, 7, 8 }; 16 int a3[ SIZE2 ] = { 4, 5, 6, 11, 15 }; 17 std::ostream_iterator< int > output( cout, " " ); 18 19 cout << "a1 contains: "; 20 std::copy( a1, a1 + SIZE1, output ); 21 cout << "\na2 contains: "; 22 std::copy( a2, a2 + SIZE2, output ); 23 cout << "\na3 contains: "; 24 std::copy( a3, a3 + SIZE2, output ); 25

 2003 Prentice Hall, Inc. All rights reserved. 126 26 // determine whether set a2 is completely contained in a1 Outline 27 if ( std::includes( a1, a1 + SIZE1, a2, a2 + SIZE2 ) ) 28 cout << "\n\na1 includes a2"; 29 else fig21_35.cpp 30 cout << "\n\na1 does not include a2"; (2 of 3) 31 32 // determine whether set a3 is completely contained in a1 33 if ( std::includes( a1, a1 + SIZE1, a3, a3 + SIZE2 ) ) 34 cout << "\na1 includes a3"; 35 else 36 cout << "\na1 does not include a3"; 37 38 int difference[ SIZE1 ]; 39 40 // determine elements of a1 not in a2 41 int *ptr = std::set_difference( a1, a1 + SIZE1, 42 a2, a2 + SIZE2, difference ); 43 44 cout << "\n\nset_difference of a1 and a2 is: "; 45 std::copy( difference, ptr, output ); 46 47 int intersection[ SIZE1 ]; 48 49 // determine elements in both a1 and a2 50 ptr = std::set_intersection( a1, a1 + SIZE1, 51 a2, a2 + SIZE2, intersection ); 52  2003 Prentice Hall, Inc. All rights reserved. 127 53 cout << "\n\nset_intersection of a1 and a2 is: "; Outline 54 std::copy( intersection, ptr, output ); 55 56 int symmetric_difference[ SIZE1 ]; fig21_35.cpp 57 (3 of 3) 58 // determine elements of a1 that are not in a2 and 59 // elements of a2 that are not in a1 60 ptr = std::set_symmetric_difference( a1, a1 + SIZE1, 61 a2, a2 + SIZE2, symmetric_difference ); 62 63 cout << "\n\nset_symmetric_difference of a1 and a2 is: "; 64 std::copy( symmetric_difference, ptr, output ); 65 66 int unionSet[ SIZE3 ]; 67 68 // determine elements that are in either or both sets 69 ptr = std::set_union( a1, a1 + SIZE1, 70 a3, a3 + SIZE2, unionSet ); 71 72 cout << "\n\nset_union of a1 and a3 is: "; 73 std::copy( unionSet, ptr, output ); 74 75 cout << endl; 76 77 return 0; 78 79 } // end main  2003 Prentice Hall, Inc. All rights reserved. 128 a1 contains: 1 2 3 4 5 6 7 8 9 10 Outline a2 contains: 4 5 6 7 8 a3 contains: 4 5 6 11 15 fig21_35.cpp a1 includes a2 output (1 of 1) a1 does not include a3 set_difference of a1 and a2 is: 1 2 3 9 10 set_intersection of a1 and a2 is: 4 5 6 7 8 set_symmetric_difference of a1 and a2 is: 1 2 3 9 10 set_union of a1 and a3 is: 1 2 3 4 5 6 7 8 9 10 11 15

• lower_bound(iter1, iter2, value) – For sorted elements, returns iterator to the first location where value could be inserted and elements remain sorted • upper_bound(iter1, iter2, value) – Same as lower_bound, but returns iterator to last element where value could be inserted • equal_range(iter1, iter2, value) – Returns two iterators, a lower_bound and an upper_bound – Assign them to a pair object

 2003 Prentice Hall, Inc. All rights reserved. 130 1 // Fig. 21.36: fig21_36.cpp Outline 2 // Standard library functions lower_bound, upper_bound and 3 // equal_range for a sorted sequence of values. 4 #include 5 fig21_36.cpp 6 using std::cout; (1 of 4) 7 using std::endl; 8 9 #include // algorithm definitions 10 #include // vector class-template definition 11 12 int main() 13 { 14 const int SIZE = 10; 15 int a1[] = { 2, 2, 4, 4, 4, 6, 6, 6, 6, 8 }; 16 std::vector< int > v( a1, a1 + SIZE ); 17 std::ostream_iterator< int > output( cout, " " ); 18 19 cout << "Vector v contains:\n"; 20 std::copy( v.begin(), v.end(), output ); 21 22 // determine lower-bound insertion point for 6 in v 23 std::vector< int >::iterator lower; 24 lower = std::lower_bound( v.begin(), v.end(), 6 ); 25

 2003 Prentice Hall, Inc. All rights reserved. 131 26 cout << "\n\nLower bound of 6 is element " Outline 27 << ( lower - v.begin() ) << " of vector v"; 28 29 // determine upper-bound insertion point for 6 in v 30 std::vector< int >::iterator upper; fig21_36.cpp 31 upper = std::upper_bound( v.begin(), v.end(), 6 ); (2 of 4) 32 33 cout << "\nUpper bound of 6 is element " 34 << ( upper - v.begin() ) << " of vector v"; 35 36 // use equal_range to determine both the lower- and 37 // upper-bound insertion points for 6 38 std::pair< std::vector< int >::iterator, 39 std::vector< int >::iterator > eq; 40 eq = std::equal_range( v.begin(), v.end(), 6 ); 41 42 cout << "\nUsing equal_range:\n" 43 << " Lower bound of 6 is element " 44 << ( eq.first - v.begin() ) << " of vector v"; 45 cout << "\n Upper bound of 6 is element " 46 << ( eq.second - v.begin() ) << " of vector v"; 47 48 cout << "\n\nUse lower_bound to locate the first point\n" 49 << "at which 5 can be inserted in order"; 50

 2003 Prentice Hall, Inc. All rights reserved. 132 51 // determine lower-bound insertion point for 5 in v Outline 52 lower = std::lower_bound( v.begin(), v.end(), 5 ); 53 54 cout << "\n Lower bound of 5 is element " 55 << ( lower - v.begin() ) << " of vector v"; 56 fig21_36.cpp 57 cout << "\n\nUse upper_bound to locate the last point\n" (3 of 4) 58 << "at which 7 can be inserted in order"; 59 60 // determine upper-bound insertion point for 7 in v 61 upper = std::upper_bound( v.begin(), v.end(), 7 ); 62 63 cout << "\n Upper bound of 7 is element " 64 << ( upper - v.begin() ) << " of vector v"; 65 66 cout << "\n\nUse equal_range to locate the first and\n" 67 << "last point at which 5 can be inserted in order"; 68 69 // use equal_range to determine both the lower- and 70 // upper-bound insertion points for 5 71 eq = std::equal_range( v.begin(), v.end(), 5 ); 72 73 cout << "\n Lower bound of 5 is element " 74 << ( eq.first - v.begin() ) << " of vector v"; 75 cout << "\n Upper bound of 5 is element " 76 << ( eq.second - v.begin() ) << " of vector v" 77 << endl;  2003 Prentice Hall, Inc. All rights reserved. 133 78 Outline 79 return 0; 80 81 } // end main fig21_36.cpp

Vector v contains: (4 of 4) 2 2 4 4 4 6 6 6 6 8 fig21_36.cpp Lower bound of 6 is element 5 of vector v output (1 of 1) Upper bound of 6 is element 9 of vector v Using equal_range: Lower bound of 6 is element 5 of vector v Upper bound of 6 is element 9 of vector v

Use lower_bound to locate the first point at which 5 can be inserted in order Lower bound of 5 is element 5 of vector v

Use upper_bound to locate the last point at which 7 can be inserted in order Upper bound of 7 is element 9 of vector v

Use equal_range to locate the first and last point at which 5 can be inserted in order Lower bound of 5 is element 5 of vector v Upper bound of 5 is element 5 of vector v

• Heapsort - sorting algorithm – Heap binary tree – Largest element at top of heap – Children always less than parent node – make_heap(iter1, iter2) • Creates a heap in the range of the iterators • Must be random access iterators (arrays, vectors, deques) – sort_heap(iter1, iter2) • Sorts a heap sequence from iter1 to iter2

• Functions – push_heap(iter1, iter2) • The iterators must specify a heap • Adds last element in object to heap – Assumes other elements already in heap order – pop_heap(iter1, iter2) • Removes the top element of a heap and puts it at the end of the container. • Function checks that all other elements still in a heap • Range of the iterators must be a heap. • If all the elements popped, sorted list

 2003 Prentice Hall, Inc. All rights reserved. 136 1 // Fig. 21.37: fig21_37.cpp Outline 2 // Standard library algorithms push_heap, pop_heap, 3 // make_heap and sort_heap. 4 #include fig21_37.cpp 5 (1 of 3) 6 using std::cout; 7 using std::endl; 8 9 #include 10 #include 11 12 int main() 13 { 14 const int SIZE = 10; 15 int a[ SIZE ] = { 3, 100, 52, 77, 22, 31, 1, 98, 13, 40 }; 16 std::vector< int > v( a, a + SIZE ), v2; 17 std::ostream_iterator< int > output( cout, " " ); 18 19 cout << "Vector v before make_heap:\n"; Create a new heap. 20 std::copy( v.begin(), v.end(), output ); 21 22 // create heap from vector v 23 std::make_heap( v.begin(), v.end() ); 24 25 cout << "\nVector v after make_heap:\n"; 26 std::copy( v.begin(), v.end(), output );

 2003 Prentice Hall, Inc. All rights reserved. 137 27 Outline 28 // sort elements of v with sort_heap 29 std::sort_heap( v.begin(), v.end() ); 30 fig21_37.cpp 31 cout << "\nVector v after sort_heap:\n"; (2 of 3) 32 std::copy( v.begin(), v.end(), output ); 33 34 // perform the heapsort with push_heap and pop_heap 35 cout << "\n\nArray a contains: "; 36 std::copy( a, a + SIZE, output ); 37 38 cout << endl; 39 Add elements one at a time. 40 // place elements of array a into v2 and 41 // maintain elements of v2 in heap 42 for ( int i = 0; i < SIZE; ++i ) { 43 v2.push_back( a[ i ] ); 44 std::push_heap( v2.begin(), v2.end() ); 45 cout << "\nv2 after push_heap(a[" << i << "]): "; 46 std::copy( v2.begin(), v2.end(), output ); 47 48 } // end for 49 50 cout << endl; 51

 2003 Prentice Hall, Inc. All rights reserved. 138 52 // remove elements from heap in sorted order Outline 53 for ( int j = 0; j < v2.size(); ++j ) { 54 cout << "\nv2 after " << v2[ 0 ] << " popped from heap\n"; 55 std::pop_heap( v2.begin(), v2.end() - j ); 56 std::copy( v2.begin(), v2.end(), output ); fig21_37.cpp 57 (3 of 3) 58 } // end for 59 60 cout << endl; 61 62 return 0; 63 64 } // end main

 2003 Prentice Hall, Inc. All rights reserved. 139 Vector v before make_heap: Outline 3 100 52 77 22 31 1 98 13 40 Vector v after make_heap: 100 98 52 77 40 31 1 3 13 22 fig21_37.cpp Vector v after sort_heap: output (1 of 2) 1 3 13 22 31 40 52 77 98 100

Array a contains: 3 100 52 77 22 31 1 98 13 40 v2 after push_heap(a[0]): 3 v2 after push_heap(a[1]): 100 3 v2 after push_heap(a[2]): 100 3 52 v2 after push_heap(a[3]): 100 77 52 3 v2 after push_heap(a[4]): 100 77 52 3 22 v2 after push_heap(a[5]): 100 77 52 3 22 31 v2 after push_heap(a[6]): 100 77 52 3 22 31 1 v2 after push_heap(a[7]): 100 98 52 77 22 31 1 3 v2 after push_heap(a[8]): 100 98 52 77 22 31 1 3 13 v2 after push_heap(a[9]): 100 98 52 77 40 31 1 3 13 22

 2003 Prentice Hall, Inc. All rights reserved. 140 v2 after 100 popped from heap Outline 98 77 52 22 40 31 1 3 13 100 v2 after 98 popped from heap 77 40 52 22 13 31 1 3 98 100 fig21_37.cpp v2 after 77 popped from heap output (2 of 2) 52 40 31 22 13 3 1 77 98 100 v2 after 52 popped from heap 40 22 31 1 13 3 52 77 98 100 v2 after 40 popped from heap 31 22 3 1 13 40 52 77 98 100 v2 after 31 popped from heap 22 13 3 1 31 40 52 77 98 100 v2 after 22 popped from heap 13 1 3 22 31 40 52 77 98 100 v2 after 13 popped from heap 3 1 13 22 31 40 52 77 98 100 v2 after 3 popped from heap 1 3 13 22 31 40 52 77 98 100 v2 after 1 popped from heap 1 3 13 22 31 40 52 77 98 100

• min(value1, value2) – Returns smaller element • max(value1, value2) – Returns larger element

 2003 Prentice Hall, Inc. All rights reserved. 142 1 // Fig. 21.38: fig21_38.cpp Outline 2 // Standard library algorithms min and max. 3 #include 4 fig21_38.cpp 5 using std::cout; (1 of 1) 6 using std::endl; 7 8 #include 9 10 int main() 11 { 12 cout << "The minimum of 12 and 7 is: " 13 << std::min( 12, 7 ); 14 cout << "\nThe maximum of 12 and 7 is: " 15 << std::max( 12, 7 ); 16 cout << "\nThe minimum of 'G' and 'Z' is: " 17 << std::min( 'G', 'Z' ); 18 cout << "\nThe maximum of 'G' and 'Z' is: " 19 << std::max( 'G', 'Z' ) << endl; 20 21 return 0; 22 23 } // end main

 2003 Prentice Hall, Inc. All rights reserved. 143 The minimum of 12 and 7 is: 7 Outline The maximum of 12 and 7 is: 12 The minimum of 'G' and 'Z' is: G The maximum of 'G' and 'Z' is: Z fig21_38.cpp output (1 of 1)

• adjacent_difference • inner_product • partial_sum • nth_element • partition • stable_partition • next_permutation • prev_permutation • rotate • rotate_copy • adjacent_find • partial_sort • partial_sort_copy • stable_sort

• Class bitset – Represents a set of bit flags – Can manipulate bit sets • Operations – bitset b; create bitset – b.set( bitNumber) set bit bitNumber to on – b.set() all bits on – b.reset(bitNumber) set bit bitNumber to off – b.reset() all bits off – b.flip(bitNumber) flip bit (on to off, off to on) – b.flip() flip all bits – b[bitNumber] returns reference to bit – b.at(bitNumber) range checking, returns reference

• Operations • b.test(bitNumber) has range checking; if bit on, returns true • b.size() size of bitset • b.count() number of bits set to on • b.any() true if any bits are on • b.none() true if no bits are on • can use &=, |=, !=, <<=, >>= – b &= b1 – Logical AND between b and b1, result in b • b.to_string() convert to string • b.to_ulong() convert to long

 2003 Prentice Hall, Inc. All rights reserved. 147 1 // Fig. 21.40: fig21_40.cpp Outline 2 // Using a bitset to demonstrate the Sieve of Eratosthenes. 3 #include 4 fig21_40.cpp 5 using std::cin; (1 of 3) 6 using std::cout; 7 using std::endl; 8 9 #include 10 11 using std::setw; 12 13 #include // bitset class definition 14 #include // sqrt prototype 15 16 int main() 17 { 18 const int size = 1024; 19 int value; 20 std::bitset< size > sieve; 21 22 sieve.flip(); 23

 2003 Prentice Hall, Inc. All rights reserved. 148 24 // perform Sieve of Eratosthenes Outline 25 int finalBit = sqrt( sieve.size() ) + 1; Sieve of Eratosthenes: turn off 26 bits for all multiples of a 27 for ( int i = 2; i < finalBit; ++i ) number. What bits remfigain21_ ar40e .cpp 28 prime. (2 of 3) 29 if ( sieve.test( i ) ) 30 31 for ( int j = 2 * i; j < size; j += i ) 32 sieve.reset( j ); 33 34 cout << "The prime numbers in the range 2 to 1023 are:\n"; 35 36 // display prime numbers in range 2-1023 37 for ( int k = 2, counter = 0; k < size; ++k ) 38 39 if ( sieve.test( k ) ) { 40 cout << setw( 5 ) << k; 41 42 if ( ++counter % 12 == 0 ) 43 cout << '\n'; 44 45 } // end outer if 46 47 cout << endl; 48

 2003 Prentice Hall, Inc. All rights reserved. 149 49 // get value from user to determine whether value is prime Outline 50 cout << "\nEnter a value from 1 to 1023 (-1 to end): "; 51 cin >> value; 52 fig21_40.cpp 53 while ( value != -1 ) { (3 of 3) 54 55 if ( sieve[ value ] ) 56 cout << value << " is a prime number\n"; 57 else 58 cout << value << " is not a prime number\n"; 59 60 cout << "\nEnter a value from 2 to 1023 (-1 to end): "; 61 cin >> value; 62 63 } // end while 64 65 return 0; 66 67 } // end main

 2003 Prentice Hall, Inc. All rights reserved. 150 The prime numbers in the range 2 to 1023 are: Outline 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 fig21_40.cpp 157 163 167 173 179 181 191 193 197 199 211 223 output (1 of 1) 227 229 233 239 241 251 257 263 269 271 277 281 283 293 307 311 313 317 331 337 347 349 353 359 367 373 379 383 389 397 401 409 419 421 431 433 439 443 449 457 461 463 467 479 487 491 499 503 509 521 523 541 547 557 563 569 571 577 587 593 599 601 607 613 617 619 631 641 643 647 653 659 661 673 677 683 691 701 709 719 727 733 739 743 751 757 761 769 773 787 797 809 811 821 823 827 829 839 853 857 859 863 877 881 883 887 907 911 919 929 937 941 947 953 967 971 977 983 991 997 1009 1013 1019 1021

Enter a value from 1 to 1023 (-1 to end): 389 389 is a prime number

Enter a value from 2 to 1023 (-1 to end): 88 88 is not a prime number

Enter a value from 2 to 1023 (-1 to end): -1

• Function objects () – Contain functions invoked using operator()

STL function objects Type divides< T > arithmetic equal_to< T > relational greater< T > relational greater_equal< T > relational less< T > relational less_equal< T > relational logical_and< T > logical logical_not< T > logical logical_or< T > logical minus< T > arithmetic modulus< T > arithmetic negate< T > arithmetic not_equal_to< T > relational plus< T > arithmetic multiplies< T > arithmetic

 2003 Prentice Hall, Inc. All rights reserved. 152 1 // Fig. 21.42: fig21_42.cpp Outline 2 // Demonstrating function objects. 3 #include 4 5 using std::cout; fig21_42.cpp 6 using std::endl; (1 of 4) 7 8 #include // vector class-template definition 9 #include // copy algorithm 10 #include // accumulate algorithm 11 #include // binary_function definition Create a function to be used 12 with accumulate. 13 // binary function adds square of its second argument and 14 // running total in its first argument, then returns sum 15 int sumSquares( int total, int value ) 16 { 17 return total + value * value; 18 19 } // end function sumSquares 20

 2003 Prentice Hall, Inc. All rights reserved. 153 21 // binary function class template defines overloaded operator() Outline 22 // that adds suare of its second argument and running total in 23 // its first argument, then returns sum 24 template< class T > 25 class SumSquaresClass : public std::binary_function< T, T, T > { fig21_42.cpp 26 C r eate a function (o2b ojectf 4 )(it 27 public: can also encapsulate data). 28 Ov er lo ad operator(). 29 // add square of value to total and return result 30 const T operator()( const T &total, const T &value ) 31 { 32 return total + value * value; 33 34 } // end function operator() 35 36 }; // end class SumSquaresClass 37

 2003 Prentice Hall, Inc. All rights reserved. 154 38 int main() Outline 39 { 40 const int SIZE = 10; 41 int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; 42 fig21_42.cpp 43 std::vector< int > integers( array, array + SIZE ); (3 of 4) 44 45 std::ostream_iterator< int > output( cout, " " ); 46 47 int result = 0; 48 accumulate initially passes 49 cout << "vector v contains:\n"; 0 as the first argument, with 50 std::copy( integers.begin(), integers.end(), output ); the first element as the 51 second. It then uses the return 52 // calculate sum of squares of elements of vector integers value as the first argument, 53 // using binary function sumSquares and iterates through the other 54 result = std::accumulate( integers.begin(), integers.end(), elements. 55 0, sumSquares ); 56 57 cout << "\n\nSum of squares of elements in integers using " 58 << "binary\nfunction sumSquares: " << result; 59

 2003 Prentice Hall, Inc. All rights reserved. 155 60 // calculate sum of squares of elements of vector integers Outline 61 // using binary-function object 62 result = std::accumulate( integers.begin(), integers.end(), 63 0, SumSquaresClass< int >() ); fig21_42.cpp 64 (4 of 4) 65 cout << "\n\nSum of squares of elements in integers using " 66 << "binary\nfunction object of type " fig21_42.cpp 67 << "SumSquaresClass< int >: " << result << endl; output (1 of 1) 68 Use accumulate with a 69 return 0; function object. 70 71 } // end main vector v contains: 1 2 3 4 5 6 7 8 9 10

Sum of squares of elements in integers using binary function sumSquares: 385

Sum of squares of elements in integers using binary function object of type SumSquaresClass< int >: 385