Function definitions

The elements of a function definition are as follows:

Function storage class specifiers, which specify linkage
Function return type specifiers, which specify the data type of a value to be returned
Function specifiers, which specify additional properties for functions
Function declarators, which include function identifiers as well as lists of parameters
The function body, which is a braces-enclosed series of statements representing the actions that the function performs
Constructor-initializers, which are used only in constructor functions declared in classes; they are described in Constructors (C++ only).
Try blocks, which are used in class functions; they are described in try blocks (C++ only).

IBM extension begins In addition, for compatibility with GNU C and C++, XL C/C++ allows you to use attributes to modify the properties of functions. They are described in Function attributes (IBM extension). IBM extension ends

Function definitions take the following form:


Function definition syntax (C only)

>>-+-------------------------+--+--------------------+---------->
   '-storage_class_specifier-'  '-function_specifier-'   

>--+-----------------------+--function_declarator--{------------>
   '-return_type_specifier-'                           

>--function body--}--------------------------------------------><


Function definition syntax (C++ only)

>>-+-------------------------+--+--------------------+---------->
   '-storage_class_specifier-'  '-function_specifier-'   

>--return_type_specifier--function_declarator------------------->

>--+-+----------------------------+-{--function body--}-+------><
   | '-:--constructor-initializer-'                     |   
   +-try-block------------------------------------------+   
   |             (1)                                    |   
   +- = default;----------------------------------------+   
   |            (2)                                     |   
   '- = delete;-----------------------------------------'

Notes:

This syntax is valid only in the C++11 standard.
This syntax is valid only in the C++11 standard.

Note: When function_declarator incorporates a trailing return type, return_type_specifer must be auto. For more information about trailing return type, see Trailing return type (C++11).