Variadic Functions

Overview

Variadic functions are functions which can take in a variable number of arguments. The C language by itself provides no special syntax for dealing with them, but variadic functions are supported by the standard C library ( <varargs.h>).

Syntax

A variadic function is declared as:

Where MyFunction is defined as a function which takes 1 required argument, and as many non-optional arguments as you want (up to the practical limit set by the maximum number of function arguments you are allowed).

A variadic function is defined as:

But how do you access the variable arguments in your function definition? Use the function-like macros va_start, va_arg and va_end provided by <varargs.h>.

The second argument passed to va_arg, type, must be a self-promoting type.

For most compilers, va_end does nothing (including the GCC compiler). But you should always include it for portability reasons.

Posted: July 10th, 2014 at 4:24 pm
Last Updated on: July 10th, 2014 at 4:50 pm