ASPRINTF(3) Linux Programmer s Manual ASPRINTF(3)

NAME asprintf, vasprintf - print to allocated string

SYNOPSIS #define _GNU_SOURCE #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, 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 is undefined.

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), feature_test_macros(7)

COLOPHON This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at

GNU 2001-12-18 ASPRINTF(3)