NAME

vasprintf, vdprintf, vfprintf, vprintf, vsnprintf, vsprintf — format output of a stdarg argument list

SYNOPSIS

#include <stdarg.h>
#include <stdio.h>



[CX] int vasprintf(char **restrict ptr, const char *restrict format,
       va_list ap);
int vdprintf(int fildes, const char *restrict format, va_list ap);

int vfprintf(FILE *restrict stream, const char *restrict format,
       va_list ap);
int vprintf(const char *restrict format, va_list ap);
int vsnprintf(char *restrict s, size_t n, const char *restrict format,
       va_list ap);
int vsprintf(char *restrict s, const char *restrict format, va_list ap);

DESCRIPTION

^[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2024 defers to the ISO C standard.

The ^[CX] vasprintf(), vdprintf(), vfprintf(), vprintf(), vsnprintf(), and vsprintf() functions shall be equivalent to the ^[CX] asprintf(), dprintf(), fprintf(), printf(), snprintf(), and sprintf() functions respectively, except that instead of being called with a variable number of arguments, they are called with an argument list as defined by <stdarg.h>.

These functions shall not invoke the va_end macro. As these functions invoke the va_arg macro, the value of ap after the return is unspecified.

RETURN VALUE

Refer to fprintf .

ERRORS

Refer to fprintf .

EXAMPLES

None.

APPLICATION USAGE

Applications using these functions should call va_end(ap) afterwards to clean up.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

2.5 Standard I/O Streams , fprintf

XBD <stdarg.h> , <stdio.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 5

The vsnprintf() function is added.

Issue 6

The vfprintf(), vprintf(), vsnprintf(), and vsprintf() functions are updated for alignment with the ISO/IEC 9899:1999 standard.

Issue 7

The vdprintf() function is added to complement the dprintf() function from The Open Group Technical Standard, 2006, Extended API Set Part 1.

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0703 [14] is applied.

Issue 8

Austin Group Defect 1496 is applied, adding the vasprintf() function.