ASPRINTF(3) Linux Programmer's Manual ASPRINTF(3)
NAME
asprintf, vasprintf - print to allocated string
SYNOPSIS
#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);
DESCRIPTION
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.
RETURN VALUE
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.
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
+------------------------+---------------+----------------+
|Interface | Attribute | Value |
+------------------------+---------------+----------------+
|asprintf(), vasprintf() | Thread safety | MT-Safe locale |
+------------------------+---------------+----------------+
CONFORMING TO
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.
SEE ALSO
free(3), malloc(3), printf(3)
COLOPHON
This page is part of release 5.07 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
GNU 2019-03-06 ASPRINTF(3)