asprintf(3) — Linux manual page

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
       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 │
       └──────────────────────────────┴───────────────┴────────────────┘

VERSIONS

       The FreeBSD implementation sets strp to NULL on error.

STANDARDS

       GNU, BSD.

SEE ALSO

       free(3), malloc(3), printf(3)

COLOPHON

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Linux man-pages 6.9.1          2024-06-15                    asprintf(3)

Pages that refer to this page: lttng_ust_tracef(3), lttng_ust_tracelog(3), printf(3), printf.h(3head)

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