编程参考 - C语言可变参数

Variadic functions - cppreference.com

Variadic functions

Variadic functions are functions (e.g. printf) which take a variable number of arguments.

The declaration of a variadic function uses an ellipsis as the last parameter, e.g.

int printf(const char* format, ...);. See variadic arguments for additional detail on the syntax and automatic argument conversions.

Accessing the variadic arguments from the function body uses the following library facilities:

Types

va_list: holds the information needed by va_start, va_arg, va_end, and va_copy (typedef)

Macros

Defined in header <stdarg.h>

va_start:
enables access to variadic function arguments
(function macro)

va_arg:
accesses the next variadic function argument
(function macro)

va_copy:
(C99)
makes a copy of the variadic function arguments
(function macro)

va_end:
ends traversal of the variadic function arguments
(function macro)

Example

Run online compiler: Coliru

Print values of different types.

 

#include <stdarg.h> #include <stdio.h> void simple_printf(const char* fmt, ...) {     va_list args;     for (va_start(args, fmt); *fmt != '\0'; ++fmt)     {         switch(*fmt)         {             case 'd':             {                 int i = va_arg(args, int);