vasprintf(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 4.09 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/.

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