vasprintf

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 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 5.08 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)