String Data Type Recall that most programming languages have primitive data types. These are simple to describe and store in RAM, such as integer, character, and boolean. A string is a collection of one or more characters. A string is a complex data type, since it is constructed from multiple primitive data elements. Declaring Strings & Assigning Values Turing Java var str1 : string := "hello" String str1 = "hello"; var str2 : string String str2; str2 := "goodbye" str2 = "goodbye"; put str1 println(str1); put str2 println(str2); put "literal" println("literal"); Strings as Collections of Characters Turing Java Start counting at one: Start counting at zero: "hello" "hello" 12345 01234 "goodbye" "goodbye" 1234567 0123456 Length of a String (number of characters) Turing Java var str1 : string String str1; var len : int int len; str1 := "hello" str1 = "hello"; len := length(str1) len = str1.length(); put "String is: ", str1 println(str1); put "Length: ", len println(len); Comparing Strings Turing Java var str1, str2 : string String str1, str2; var same : boolean boolean same; str1 := "hello" str1 = "hello"; str2 := "goodbye" str2 = "goodbye"; same := str1 = str2 same = str1.equals(str2); if (str1 = str2) if (str1.equals(str2)) put "Same!" println("Same!"); end if end if Concatenate (join) Strings Java Turing String str1, str2, str3; var str1, str2, str3 : string str1 = "hello"; str1 := "hello" str2 = "goodbye"; str2 := "goodbye" str3 = str1 + str2; str3 := str1 + str2 // OR str3 = str1.concat(str2); String to Upper Case Turing Java var str1, str2 : string String str1, str2; str1 := "Hello" str1 = "hello"; % 12345 // 01234 str2 := Str.Upper(str1) str2 = str1.toUpperCase(); println(str2); put str2 // output is "HELLO" % output is "HELLO" String to Lower Case Turing Java var str1, str2 : string String str1, str2; str1 := "Hello" str1 = "HelLo"; % 12345 // 01234 str2 := Str.Lower(str1) str2 = str1.toLowerCase(); println(str2); put str2 // output is "hello" % output is "hello" Convert a String to a Number Turing Java var str1 : string String str1; var num : int int num; str1 := "123" str1 = "123"; num := strint(str1) num=Integer.parseInt(str1); println(num); // 123 put num % 123 println(num+1); // 124 put num+1 % 124 Test if String to Number Possible Turing var str1 : string var num : int str1 := "123" if strintok(str1) then num := strint(str1) put num % 123 put num+1 % 124 end if Single Element (character) from a String Turing Java var str1 : string String str1; var ch : char char ch; str1 := "hello" str1 = "hello"; % 12345 // 01234 ch := str1(2) % 'e' ch = str1.charAt(1); put ch println(ch); put str1(2) println(str1.charAt(1)); Traverse String (visit one character at a time) Java Turing String str1; var str1 : string char ch; var ch : char str1 = "hello"; str1 := "hello" // 01234 % 12345 for (int i=0; i<str1.length(); i++) for i : 1 .. length(str1) { ch := str1(i) ch = str1.charAt(i); put ch println(ch); end for } Substring by Traversing (visit one character at a time) Turing Java var str1, str2 : string String str1, str2; var ch : char char ch; str1 := "hello" str1 = "hello"; % 12345 // 01234 str2 := "" % null str str2 = ""; // null str for i : 2 .. 4 for (int i=1; i<4; i++) ch := str1(i) { str2 := str2 + ch ch = str1.charAt(i); end for str2 = str2 + ch; } put str2 println(str2); Substring using Functions Turing Java var str1, str2 : string String str1, str2; str1 := "hello" str1 = "hello"; % 12345 // 01234 str2 := str1(2..4) str2 = st1.substring(1,4); put str2 println(str2); % output is "ell" // output is "ell" Search for Char by Traversing (visit one character at a time) Turing Java var str1 : string var ch, find : char String str1; char ch, find; str1 := "hello" % 12345 str1 = "hello"; find := 'l' // 01234 find = 'l'; for i : 1 .. length(str1) for (int i=1; i<str1.length(); i++) ch := str1(i) { if (ch = find) then ch = str1.charAt(i); if (ch==find) put find, " at ", i { end if println(""+find+" at "+i); } end for } Search for Specific Character Location within String Turing Java var str1 : string String str1; var loc : int int loc; str1 := "Hello" str1 = "hello"; % 12345 // 01234 loc := index(str1,'l') loc=str1.indexOf('l'); put loc println(loc); % output is 3 // output is 2 .