![function prototype function prototype](https://2.bp.blogspot.com/_annTPGBcsB4/TAHB2IkuHhI/AAAAAAAADlQ/fUrI5Ra0tbI/s1600/IMGP2162.jpg)
For example, the following declaration is legal: int add( int a, int ) For example, if you specify the static storage-class specifier in a prototype, you must also specify the static storage class in the function definition.Ĭomplete parameter declarations ( int a) can be mixed with abstract declarators ( int) in the same declaration. Then, function calls that precede the function definition (or that occur in other source files) can be checked for argument-type and return-type mismatches. You can detect errors of this kind by declaring complete function prototypes for all functions.Ī prototype establishes the attributes of a function. This error creates problems not only with the long parameter, but with any parameters that follow it. For example, on a 16-bit computer, if a 16-bit pointer is passed as an argument, then declared as a long parameter, the first 32 bits on the stack are interpreted as a long parameter. A type mismatch between an argument and a parameter may cause the arguments on the stack to be misinterpreted. The converted type of each parameter determines the interpretation of the arguments that the function call places on the stack. The parameter list is used to check that arguments in the function call match the parameters in the function definition. Prototypes are used to initialize pointers to functions before those functions are defined. Without complete prototypes, standard conversions are made, but no attempt is made to check the type or number of arguments with the number of parameters. Although functions that return int values don't require prototypes, prototypes are recommended. They establish the return type for functions that return types other than int. In either case, the return type must agree with the return type specified in the function definition.įunction prototypes have the following important uses:
![function prototype function prototype](https://i.stack.imgur.com/eaZgP.png)
The prototype has the same form as the function definition, except that it is terminated by a semicolon immediately following the closing parenthesis and therefore has no body. Type-qualifier declaration-specifiers optĭirect-declarator: /* A function declarator */ĭirect-declarator ( parameter-type-list ) /* New-style declarator */ĭirect-declarator ( identifier-list opt ) /* Obsolete-style declarator */
![function prototype function prototype](https://image.slidesharecdn.com/icanfunctionprototype-userexperiences-171127150509/95/i-can-function-prototype-user-experiences-1-638.jpg)
Type-specifier declaration-specifiers opt Storage-class-specifier declaration-specifiers opt * attribute-seq opt is Microsoft-specific */ Syntaxĭeclaration-specifiers attribute-seq opt init-declarator-list opt To be a prototype, the function declaration must also establish types and identifiers for the function's arguments. A function declaration precedes the function definition and specifies the name, return type, storage class, and other attributes of a function.