ASPRINTF
Section: Linux Programmer's Manual (3)
Updated: 2019-03-06
Page Index
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
attributes(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 5.10 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/.