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.