asprintf(3)                                           Library Functions Manual                                          asprintf(3)

NAME
       asprintf, vasprintf - print to allocated string

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #define _GNU_SOURCE         /* See feature_test_macros(7) */
       #include <stdio.h>

       int asprintf(char **restrict strp, const char *restrict fmt, ...);
       int vasprintf(char **restrict strp, const char *restrict 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 pos‐
       sible, 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 │
       └──────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴────────────────┘

STANDARDS
       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)

Linux man-pages 6.03                                         2023-02-05                                                 asprintf(3)