Name

vprintf, vfprintf, vsprintf − print formatted output of a varargs argument list

Syntax

#include <stdio.h>
#include <varargs.h>

int vprintf ( format, ap )
char *format;
va list ap;

int vfprintf ( stream, format, ap )
FILE *stream;
char *format;
va list ap;

int vsprintf ( s, format, ap )
char *s, *format;
va list ap;

Description

The international functions vprintf, vfprintf, and vsprintf are similar to the vprintf standard I/O functions.

Likewise, the vprintf functions are similar to the printf functions except they are called with an argument list as defined by varargs instead of with a variable number of arguments.

The international functions allow you to use the %digit$ conversion character in place of the % character  you use in the standard I/O functions.  The digit is a decimal digit n from 1 to 9.  The international functions apply conversions to the nth argument in the argument list, rather than to the next unused argument. 

You can use the % conversion character in the international functions.  However, you cannot mix the % conversion character with the %digit$ conversion character in a single call. 

You can indicate a field width or precision by an asterisk (*) instead of a digit string in format strings containing the % conversion character. If you use an asterisk, you can supply an integer arg that specifies the field width or precision.  In format strings containing the %digit$ conversion character, you can indicate field width or precision by the sequence *digit$.  You use a decimal digit from 1 to 9 to indicate which argument contains an integer that specifies the field width or precision. 

The conversion characters and their meanings are identical to printf.

You must use each digit argument at least once. 

Examples

#include <stdio.h>
#include <varargs.h>
 main()
{
char *function_name = "vpr";
char *arg1 = "hello world";
int arg2 = 2;
char *arg3 = "study";
 char *i18nfmt = "%1$s %3$d\n";
 test(function_name, i18nfmt, arg1, arg2, arg3);
}
 test(va_alist)
va_dcl
{
va_list args;
char *fmt;
char string[1024];
 va_start(args);
 (void)printf("function %s: ", va_arg(args, char *));
 fmt = va_arg(args, char *);
 (void)vprintf(fmt, args);
 va_end(args);
}

See Also

setlocale(3), scanf(3int), printf(3s), printf(3int), vprintf(3s), putc(3s), scanf(3s), stdio(3s), varargs(3)
Guide to Developing International Software