Variadic functions
From cppreference.com
< c
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:
Contents
Types
Macros
Defined in header
<stdarg.h> [edit] Example
Print values of different types.
Run this code
#include <stdarg.h> #include <stdio.h> void simple_printf(const char* fmt, ...) { va_list args; for (va_start(args, fmt); *fmt != '0円'; ++fmt) { switch(*fmt) { case 'd': { int i = va_arg(args, int); printf ("%d\n", i); break; } case 'c': { // A 'char' variable will be promoted to 'int' // A character literal in C is already 'int' by itself int c = va_arg(args, int); printf ("%c\n", c); break; } case 'f': { double d = va_arg(args, double); printf ("%f\n", d); break; } default: puts ("Unknown formatter!"); goto END; } } END: va_end(args); } int main(void) { simple_printf("dcff", 3, 'a', 1.969, 42.5); }
Output:
3 a 1.969000 42.50000
[edit] References
- C23 standard (ISO/IEC 9899:2024):
- 7.16 Variable arguments <stdarg.h> (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.16 Variable arguments <stdarg.h> (p: TBD)
- C11 standard (ISO/IEC 9899:2011):
- 7.16 Variable arguments <stdarg.h> (p: 269-272)
- C99 standard (ISO/IEC 9899:1999):
- 7.15 Variable arguments <stdarg.h> (p: 249-252)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.8 VARIABLE ARGUMENTS <stdarg.h>
[edit] See also
C++ documentation for Variadic functions