asprintf, vasprintf - print to allocated string
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <stdio.h>
int asprintf(char **strp, const char *fmt,
...);
int vasprintf(char **strp, const char *fmt,
va_list ap);
The functions
asprintf() and
vasprintf() are analogs of
sprintf(3) and
vsprintf(3), except that they allocate a string
large enough to hold the output including the terminating null byte ('\0'),
and return a pointer to it via the first argument. This pointer should be
passed to
free(3) to release the allocated storage when it is no longer
needed.
When successful, these functions return the number of bytes printed, just like
sprintf(3). If memory allocation wasn't possible, or some other error
occurs, these functions will return -1, and the contents of
strp are
undefined.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| asprintf (), vasprintf () |
Thread safety |
MT-Safe locale |
These functions are GNU extensions, not in C or POSIX. They are also available
under *BSD. The FreeBSD implementation sets
strp to NULL on error.
free(3),
malloc(3),
printf(3)