NAME

       asprintf, vasprintf - print to allocated string

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  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 5.13 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/.