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| .\" Text fragments inspired by Martin Schulze <joey@infodrom.org>. |
| .\" |
| .TH ASPRINTF 3 2015-04-19 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| asprintf, vasprintf \- print to allocated string |
| .SH SYNOPSIS |
| .BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */" |
| .br |
| .B #include <stdio.h> |
| .sp |
| .BI "int asprintf(char **" strp ", const char *" fmt ", ...);" |
| .sp |
| .BI "int vasprintf(char **" strp ", const char *" fmt ", va_list " ap ); |
| .SH DESCRIPTION |
| The functions |
| .BR asprintf () |
| and |
| .BR vasprintf () |
| are analogs of |
| .BR sprintf (3) |
| and |
| .BR vsprintf (3), |
| except that they allocate a string large enough to hold the output |
| including the terminating null byte (\(aq\\0\(aq), |
| and return a pointer to it via the first argument. |
| This pointer should be passed to |
| .BR free (3) |
| to release the allocated storage when it is no longer needed. |
| .SH RETURN VALUE |
| When successful, these functions return the number of bytes printed, |
| just like |
| .BR sprintf (3). |
| If memory allocation wasn't possible, or some other error occurs, |
| these functions will return \-1, and the contents of |
| .I strp |
| are undefined. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .TS |
| allbox; |
| lbw23 lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR asprintf (), |
| .BR vasprintf () |
| T} Thread safety MT-Safe locale |
| .TE |
| |
| .SH CONFORMING TO |
| These functions are GNU extensions, not in C or POSIX. |
| They are also available under *BSD. |
| The FreeBSD implementation sets |
| .I strp |
| to NULL on error. |
| .SH SEE ALSO |
| .BR free (3), |
| .BR malloc (3), |
| .BR printf (3) |