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5. Data Types
IEEE FOR THE FUNCTIONAL VERIFICATION LANGUAGE e Std 1647-2011 5. Data types The e language has a number of predefined data types, including the integer and Boolean scalar types common to most programming languages. In addition, new scalar data types (enumerated types) that are appropriate for programming, modeling hardware, and interfacing with hardware simulators can be created. The e language also provides a powerful mechanism for defining OO hierarchical data structures (structs) and ordered collections of elements of the same type (lists). The following subclauses provide a basic explanation of e data types. 5.1 e data types Most e expressions have an explicit data type, as follows: — Scalar types — Scalar subtypes — Enumerated scalar types — Casting of enumerated types in comparisons — Struct types — Struct subtypes — Referencing fields in when constructs — List types — The set type — The string type — The real type — The external_pointer type — The “untyped” pseudo type Certain expressions, such as HDL objects, have no explicit data type. See 5.2 for information on how these expressions are handled. 5.1.1 Scalar types Scalar types in e are one of the following: numeric, Boolean, or enumerated. Table 17 shows the predefined numeric and Boolean types. Both signed and unsigned integers can be of any size and, thus, of any range. See 5.1.2 for information on how to specify the size and range of a scalar field or variable explicitly. See also Clause 4. 5.1.2 Scalar subtypes A scalar subtype can be named and created by using a scalar modifier to specify the range or bit width of a scalar type. -
Lecture 2: Variables and Primitive Data Types
Lecture 2: Variables and Primitive Data Types MIT-AITI Kenya 2005 1 In this lecture, you will learn… • What a variable is – Types of variables – Naming of variables – Variable assignment • What a primitive data type is • Other data types (ex. String) MIT-Africa Internet Technology Initiative 2 ©2005 What is a Variable? • In basic algebra, variables are symbols that can represent values in formulas. • For example the variable x in the formula f(x)=x2+2 can represent any number value. • Similarly, variables in computer program are symbols for arbitrary data. MIT-Africa Internet Technology Initiative 3 ©2005 A Variable Analogy • Think of variables as an empty box that you can put values in. • We can label the box with a name like “Box X” and re-use it many times. • Can perform tasks on the box without caring about what’s inside: – “Move Box X to Shelf A” – “Put item Z in box” – “Open Box X” – “Remove contents from Box X” MIT-Africa Internet Technology Initiative 4 ©2005 Variables Types in Java • Variables in Java have a type. • The type defines what kinds of values a variable is allowed to store. • Think of a variable’s type as the size or shape of the empty box. • The variable x in f(x)=x2+2 is implicitly a number. • If x is a symbol representing the word “Fish”, the formula doesn’t make sense. MIT-Africa Internet Technology Initiative 5 ©2005 Java Types • Integer Types: – int: Most numbers you’ll deal with. – long: Big integers; science, finance, computing. – short: Small integers. -
Chapter 5: Substitutes for C Constructs
CHAPTER 5 Substitutes for C Constructs THE Java programming language shares many similarities with the C program- ming language, but several C constructs have been omitted. In most cases, it’s obvi- ous why a C construct was omitted and how to make do without it. This chapter suggests replacements for several omitted C constructs whose replacements are not so obvious. The common thread that connects the items in this chapter is that all of the omitted constructs are data-oriented rather than object-oriented. The Java pro- gramming language provides a powerful type system, and the suggested replace- ments take full advantage of that type system to deliver a higher quality abstraction than the C constructs they replace. Even if you choose to skip this chapter, it’s probably worth reading Item 21, which discusses the typesafe enum pattern, a replacement for C’s enum construct. This pattern is not widely known at the time of this writing, and it has several advan- tages over the methods currently in common use. Item 19: Replace structures with classes The C struct construct was omitted from the Java programming language because a class does everything a structure does and more. A structure merely groups multi- ple data fields into a single object; a class associates operations with the resulting object and allows the data fields to be hidden from users of the object. In other words, a class can encapsulate its data into an object that is accessed solely by its methods, allowing the implementor the freedom to change the representation over time (Item 12). -
Source Code Auditing: Day 2
Source Code Auditing: Day 2 Penetration Testing & Vulnerability Analysis Brandon Edwards [email protected] Data Types Continued Data Type Signedness Remember, by default all data types are signed unless specifically declared otherwise But many functions which accept size arguments take unsigned values What is the difference of the types below? char y; unsigned char x; x = 255; y = -1; 3 Data Type Signedness These types are the same size (8-bits) char y; unsigned char x; 4 Data Type Signedness A large value in the unsigned type (highest bit set) is a negative value in the signed type char y; unsigned char x; 5 Data Type Bugs Same concept applies to 16 and 32 bit data types What are the implications of mixing signed & unsigned types ? #define MAXSOCKBUF 4096 int readNetworkData(int sock) { char buf[MAXSOCKBUF]; int length; read(sock, (char *)&length, 4); if (length < MAXSOCKBUF) { read(sock, buf, length); } } 6 Data Type Signedness The check is between two signed values… #define MAXSOCKBUF 4096 if (length < MAXSOCKBUF) So if length is negative (highest bit / signed bit set), it will evaluate as less than MAXSOCKBUF But the read() function takes only unsigned values for it’s size Remember, the highest bit (or signed bit is set), and the compiler implicitly converts the length to unsigned for read() 7 Data Type Signedness So what if length is -1 (or 0xFFFFFFFF in hex)? #define MAXSOCKBUF 4096 if (length < MAXSOCKBUF) { read(sock, buf, length); } When the length check is performed, it is asking if -1 is less than 4096 When the length is passed to read, it is converted to unsigned and becomes the unsigned equivalent of -1, which for 32bits is 4294967295 8 Data Type Bugs Variation in data type sizes can also introduce bugs Remember the primitive data type sizes? (x86): An integer type is 32bits A short type is 16bits A char type is 8 bits Sometimes code is written without considering differences between these. -
UML Profile for Communicating Systems a New UML Profile for the Specification and Description of Internet Communication and Signaling Protocols
UML Profile for Communicating Systems A New UML Profile for the Specification and Description of Internet Communication and Signaling Protocols Dissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultäten der Georg-August-Universität zu Göttingen vorgelegt von Constantin Werner aus Salzgitter-Bad Göttingen 2006 D7 Referent: Prof. Dr. Dieter Hogrefe Korreferent: Prof. Dr. Jens Grabowski Tag der mündlichen Prüfung: 30.10.2006 ii Abstract This thesis presents a new Unified Modeling Language 2 (UML) profile for communicating systems. It is developed for the unambiguous, executable specification and description of communication and signaling protocols for the Internet. This profile allows to analyze, simulate and validate a communication protocol specification in the UML before its implementation. This profile is driven by the experience and intelligibility of the Specification and Description Language (SDL) for telecommunication protocol engineering. However, as shown in this thesis, SDL is not optimally suited for specifying communication protocols for the Internet due to their diverse nature. Therefore, this profile features new high-level language concepts rendering the specification and description of Internet protocols more intuitively while abstracting from concrete implementation issues. Due to its support of several concrete notations, this profile is designed to work with a number of UML compliant modeling tools. In contrast to other proposals, this profile binds the informal UML semantics with many semantic variation points by defining formal constraints for the profile definition and providing a mapping specification to SDL by the Object Constraint Language. In addition, the profile incorporates extension points to enable mappings to many formal description languages including SDL. To demonstrate the usability of the profile, a case study of a concrete Internet signaling protocol is presented. -
Beaaqualogic Enterprise Security™®
BEAAquaLogic Enterprise Security™® Policy Managers Guide Version 2.6 Document Revised: April 2007 Contents 1. Introduction Document Scope and Audience. 1-1 Guide to this Document. 1-2 Related Documentation . 1-2 Contact Us! . 1-3 2. Security Policies Overview What is an AquaLogic Enterprise Security Policy? . 2-1 Closed-world Security Environment . 2-2 Policy Components . 2-3 Resources. 2-4 Virtual Resources . 2-6 Resource Attributes . 2-6 Privilege Groups. 2-6 Privileges . 2-6 Identities . 2-7 Identity Attributes. 2-8 Groups . 2-8 Users. 2-9 Roles. 2-10 Policies. 2-10 Role Mapping Policies . 2-10 Authorization Policies . 2-12 Delegation Policies. 2-13 Summary of Policy Differences . 2-14 Policy Managers Guide v Declarations. 2-14 Constants . 2-15 Enumerated Types . 2-15 Attributes . 2-15 Evaluation Functions . 2-15 3. Writing Policies Policy Implementation: Main Steps . 3-1 Access Decision Process . 3-4 Authentication Service. 3-4 Role Mapping Service . 3-4 Authorization Service . 3-5 Credential Mapping Service. 3-5 Authorization and Role Mapping Engine . 3-5 Using the Administration Console to Write Policies . 3-7 Administration Console Overview. 3-7 Defining Resources . 3-8 Virtual Resources . 3-11 Resource Attributes. 3-12 Privileges . 3-12 Privilege Groups . 3-13 Defining Identities . 3-14 Identity Attributes . 3-16 Groups. 3-16 Users . 3-17 Roles . 3-18 Writing Authorization and Role Mapping Policies . 3-19 Role Mapping Policies . 3-20 vi Policy Managers Guide Authorization Policies. 3-20 Role Mapping Policy Reports . 3-21 Authorization Policy Reports . 3-21 Defining Declarations. 3-22 Binding Policies . -
Data Types Enumerated Types
CS 1044 Intro Programming in C++ Fall 2002 August 22, 2002 Data Types 9. Types 1 data type: a collection of values and the definition of one or more operations that can be performed on those values C++ includes a variety of built-in or base data types: short, int, long, float, double, char, etc. The values are ordered and atomic. C++ supports several mechanisms for aggregate data types: arrays, structures, classes. These allow complex combinations of other types as single entities. C++ also supports other mechanisms that allow programmers to define their own custom data types: enum types and typedefs. Computer Science Dept Va Tech August, 2002 Intro Programming in C++ ©1995-2002 Barnette ND & McQuain WD Enumerated Types 9. Types 2 An enumerated type is defined by giving a name for the type and then giving a list of labels, which are the only values that a variable of that type is allowed to have. Enumerated types allow the creation of specialized types that support the use of meaningful labels within a program. They promote code readability with very little overhead in memory or runtime cost. enum Month {JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC}; enum Season {WINTER, SPRING, SUMMER, FALL}; enum Hemisphere {NORTH, SOUTH, EAST, WEST}; Month Mon; Season Period; Hemisphere Region; ... if (Mon == JAN && Region == NORTH) Period = WINTER; An enumerated type is allowed to have up to 256 values and a variable of an enumerated type will occupy one byte of memory. It is an error for the same label to be listed as a value for two different enumerated types. -
Object-Oriented Enumerated Type Facility
Europäisches Patentamt *EP001400895A2* (19) European Patent Office Office européen des brevets (11) EP 1 400 895 A2 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.7: G06F 9/44 24.03.2004 Bulletin 2004/13 (21) Application number: 03255511.2 (22) Date of filing: 03.09.2003 (84) Designated Contracting States: (72) Inventors: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR • Bloch, Joshua J. HU IE IT LI LU MC NL PT RO SE SI SK TR San José, CA 95129 (US) Designated Extension States: • Gafter, Neal M. AL LT LV MK San José, CA 95129 (US) (30) Priority: 09.09.2002 US 237941 (74) Representative: Davies, Simon Robert D Young & Co, (71) Applicant: Sun Microsystems, Inc. 21 New Fetter Lane Santa Clara, California 95054 (US) London, EC4A 1DA (GB) (54) Object-oriented enumerated type facility (57) A system and method are provided that facili- tate use of an object-oriented enumerated type within a computer program. During operation, the system re- ceives source code for the computer program. The source code contains a declaration for an enumerated type. This declaration specifies a fixed number of enu- meration constants that comprise the enumerated type. Next, the system defines the enumerated type using a class defined within an object-oriented programming language. The class includes a constant for each enu- meration constant specified in the declaration. If the declaration additionally contains one or more method declarations, these methods are present on the defined class. EP 1 400 895 A2 Printed by Jouve, 75001 PARIS (FR) EP 1 400 895 A2 Description Field of the Invention 5 [0001] The present invention relates to computer systems and to programming languages, and more specifically, to a method and an apparatus for facilitating the use of an object-oriented enumerated type within a programming lan- guage. -
Enumerated Types
Enumerated Types CSE160, Computer Science A: Honors Stony Brook University http://www.cs.stonybrook.edu/~cse160 1 Enumerated Types An enumerated type defines a list of enumerated values Each value is an identifier enum Day{SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY}; enum TrafficLight { RED, GREEN, YELLOW } A value of an enumerated type is like a constant and so, by convention, is spelled with all uppercase letters Also, by convention, an enumerated type is named like a class with first letter of each word capitalized Once a type is defined, you can declare a variable of that type: Day day; TrafficLight t; The variable day can hold one of the values defined in the enumerated type Day or null, but nothing else 2 (c) Pearson Education, Inc. & Paul Fodor (CS Stony Brook) Enumerated Types The enumerated values can be accessed using the syntax EnumeratedTypeName.valueName For example, the following statement assigns enumerated value Monday to variable day: Day day = Day.MONDAY; Using enumerated values (e.g., Day.MONDAY) rather than literal integer values (e.g., 0, 1, 2, 3, and so on) can make program easier to read and maintain An enumerated type is treated as a special class, so an enumerated type variable is therefore a reference variable An enumerated type is a subtype of the Object class (inherits all the methods in the Object class) and the Comparable interface (has the compareTo method in the Comparable interface) 3 (c) Pearson Education, Inc. & Paul Fodor (CS Stony Brook) Enumerated Types The following methods are defined for any enumerated object: public String name(); Returns a name of the value for the object (e.g. -
Software II: Principles of Programming Languages
Software II: Principles of Programming Languages Lecture 6 – Data Types Some Basic Definitions • A data type defines a collection of data objects and a set of predefined operations on those objects • A descriptor is the collection of the attributes of a variable • An object represents an instance of a user- defined (abstract data) type • One design issue for all data types: What operations are defined and how are they specified? Primitive Data Types • Almost all programming languages provide a set of primitive data types • Primitive data types: Those not defined in terms of other data types • Some primitive data types are merely reflections of the hardware • Others require only a little non-hardware support for their implementation The Integer Data Type • Almost always an exact reflection of the hardware so the mapping is trivial • There may be as many as eight different integer types in a language • Java’s signed integer sizes: byte , short , int , long The Floating Point Data Type • Model real numbers, but only as approximations • Languages for scientific use support at least two floating-point types (e.g., float and double ; sometimes more • Usually exactly like the hardware, but not always • IEEE Floating-Point Standard 754 Complex Data Type • Some languages support a complex type, e.g., C99, Fortran, and Python • Each value consists of two floats, the real part and the imaginary part • Literal form real component – (in Fortran: (7, 3) imaginary – (in Python): (7 + 3j) component The Decimal Data Type • For business applications (money) -
UNIT–IV: Pointers
Q&A for Previous Year Questions Subject: CPDS (B.Tech. I Year) Subject Code: GR11A1003 UNIT-IV ------------------------------------------------------------------------------------------------------------------------------------------ UNIT–IV: Pointers: Pointers and Addresses, Pointers and function Arguments, Pointers and arrays, Address Arithmetic, Character pointers and Functions, Pointer Arrays, Pointers to Structures, Pointers to Pointers, Command Line Arguments. Files: Introduction, Types of Files, File Access Functions, I/O on Files, Random Access to Files, Error Handling. UNIT-IV 1) What is pointer in c programming? What are its benefits? Pointer is a user defined data type that creates special types of variables which can hold the address of primitive data type like char, int, float, double or user defined data type like function, pointer etc. or derived data type like array, structure, union, enum. Examples: int *ptr; int (*ptr)(); int (*ptr)[2]; Benefits of using pointers are:- 1) Pointers are more efficient in handling arrays and data tables. 2) Pointers can be used to return multiple values from a function via function arguments. 3) The use of pointer arrays to character strings results in saving of data storage space in memory. 4) Pointers allow C to support dynamic memory management. 5) Pointers provide an efficient tool for manipulating dynamic data structures such as structures , linked lists , queues , stacks and trees. 6) Pointers reduce length and complexity of programs. 7) They increase the execution speed and thus reduce the program execution time. 2) Explain the concept of pointers? In C programming every variable keeps two type of values. 1. Value of variable. 2. Address of variable where it has stored in the memory. -
C++ DATA TYPES Rialspo Int.Co M/Cplusplus/Cpp Data Types.Htm Copyrig Ht © Tutorialspoint.Com
C++ DATA TYPES http://www.tuto rialspo int.co m/cplusplus/cpp_data_types.htm Copyrig ht © tutorialspoint.com While doing prog ramming in any prog ramming lang uag e, you need to use various variables to store various information. Variables are nothing but reserved memory locations to store values. This means that when you create a variable you reserve some space in memory. You may like to store information of various data types like character, wide character, integ er, floating point, double floating point, boolean etc. Based on the data type of a variable, the operating system allocates memory and decides what can be stored in the reserved memory. Primitive Built-in Types: C++ offer the prog rammer a rich assortment of built-in as well as user defined data types. Following table lists down seven basic C++ data types: Type Keyword Boolean bool Character char Integ er int Floating point float Double floating point double Valueless void Wide character wchar_t Several of the basic types can be modified using one or more of these type modifiers: sig ned unsig ned short long The following table shows the variable type, how much memory it takes to store the value in memory, and what is maximum and minimum vaue which can be stored in such type of variables. Type Typical Bit Width Typical Rang e char 1byte -127 to 127 or 0 to 255 unsig ned char 1byte 0 to 255 sig ned char 1byte -127 to 127 int 4bytes -2147483648 to 2147483647 unsig ned int 4bytes 0 to 4294967295 sig ned int 4bytes -2147483648 to 2147483647 short int 2bytes -32768 to 32767 unsig ned short int Rang e 0 to 65,535 sig ned short int Rang e -32768 to 32767 long int 4bytes -2,147,483,647 to 2,147,483,647 sig ned long int 4bytes same as long int unsig ned long int 4bytes 0 to 4,294,967,295 float 4bytes +/- 3.4e +/- 38 (~7 dig its) double 8bytes +/- 1.7e +/- 308 (~15 dig its) long double 8bytes +/- 1.7e +/- 308 (~15 dig its) wchar_t 2 or 4 bytes 1 wide character The sizes of variables mig ht be different from those shown in the above table, depending on the compiler and the computer you are using .