int vasprintf(char ** strp , const char * fmt , va_list ap );
DESCRIPTION
The functions
asprintf and
vasprintf are analogues of
sprintf and
vsprintf , except that they allocate a string large enough to hold the output
including the terminating NUL,
and return a pointer to it via the first parameter.
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.
NOTES
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.
