Stdarg.h

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C++ Standard Library headers
C Standard Library headers
assert.h
ctype.h
errno.h
float.h
limits.h
locale.h
math.h
setjmp.h
signal.h
stdarg.h
stddef.h
stdio.h
string.h
stdlib.h
time.h

NOTE: This also refers to varargs.h

stdarg.h is a library from the C standard library of the C programming language that serves for functions to have a variable and possibly infinite number of arguments.

Contents 1 The '...' operator 2 stdarg.h types 3 stdarg.h macros 4 Example

[edit] The '...' operator

All functions in stdarg.h or varargs.h should be in a function which has at least one "real" argument and the last argument being "..."

For example:

int check (int a, double b, ...) ;

void see (int a, ...) ;

char *wrong (...) ; //this is wrong, is must have at least one real argument

To call check, you could put

check (a, b, c, d, e) ;

check (a, b, c) ; 

check (a, b) ;

[edit] stdarg.h types

Name	Description	Compatibility
va list	type for seeing arguments	K&R C

[edit] stdarg.h macros

Name	Description	compatibility
va start	Start seeing the va_list	K&R C
va end	Stop seeing the va_list	K&R C
va copy	copy contents from a va_list to another	C99

[edit] Example

#include <stdio.h>
#ifdef LINUX //check the operative system for seeing what to include
#include <varargs.h> //linux args list macros
#else
#include <stdarg.h> //windows args list macros
#endif
void printargs (int arg1, ...) //print all int type args, finishing with -1
{
  va_list s ; //s is an argument list
  va_start (s, arg1) ; //1º arg: the va_list. 2º arg: the last "real" argument on the function
  int g = arg1 ; //the int to print, turns into the first arg
  while (g != -1) //while -1 doesn't appear
  {
    printf ("%d ", g) ; //print g
    g = va_arg (s, int) ; //1º arg: the va_list. 2º arg: the type to be seen
  }
  printf ("\n") ; //and print a new line
}
int main()
{
   printargs (5, 2, 14, 84, 97, 15, 24, 48, -1) ;
   printargs (84, 51, -1) ;
   printargs (-1) ;
   printargs (1, -1) ;
}

The following program will make the output:

5 2 14 84 97 15 24 48
84 51 

1