va_arg, va_end, va_start (ANSI)

Access variable-argument lists.

#include <stdarg.h>
#include <stdio.h>

type va_arg (va_list arg_ptr, type);

void va_end (va_list arg_ptr);

void va_start (va_list arg_ptr, prev_param);

Parameters

arg_ptr: Pointer to variable-argument list.
prev_param: Parameter preceding first optional argument.
type: Type of argument to be retrieved.

Remarks

These macros provide a portable way to access a function's arguments when the function takes a variable number of arguments. Use the va_start macro before using va_arg for the first time. The macros behave as follows:

Macro	Description
va_arg	Retrieves `type` parameter from the location given by `arg_ptr`. Increments `arg_ptr` to point to the next argument in the list, using the size of `type` parameter to determine where the next argument starts. Use this macro multiple times to retrieve all arguments from the list.
va_end	After all arguments have been retrieved, resets `arg_ptr` to a null pointer.
va_start	Sets `arg_ptr` to the first optional argument in the variable-argument list. The `arg_ptr` argument must be of the va_list type. The argument `prev_param` is the name of the required parameter immediately preceding the first optional argument in the argument list. If `prev_param` is declared with the register storage class, the macro's behavior is undefined.

The macros assume that the function takes a fixed number of required arguments, followed by a variable-argument list.

Return Values

va_arg returns the current argument.

va_start and va_end do not return values.

Requirements

Versions	Defined in	Include	Link to
INtime 3.0	intime/rt/include/stdarg.h	stdarg.h stdio.h	clib.lib

More info.

Parameters

Remarks

Return Values

Requirements

See Also