NAME
perror — write
error messages to standard error
SYNOPSIS
#include
<stdio.h>
void perror(const char *s);
DESCRIPTION
[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 (“POSIX.1”) defers to the ISO C standard.
The perror () function shall map the error
number accessed through the symbol errno to a
language-dependent error message, which shall be written to the standard
error stream as follows:
- First (if s is not a null pointer and the character pointed to by s is not the null byte), the string pointed to by s followed by a colon and a <space>.
- Then an error message string followed by a <newline>.
The contents of the error message strings shall be the same as those returned by strerror(3) with argument errno.
[CX] The
perror () function shall mark the file associated
with the standard error stream as having been written (
st_ctime,
st_mtime
marked for update) at some time between its successful completion and
exit(3), abort(3), or the completion of
fflush(3) or fclose(3) on
stderr.
The perror () function shall not change
the orientation of the standard error stream.
RETURN VALUE
The perror () function shall not return a
value.
ERRORS
No errors are defined.
EXAMPLES
Printing an Error Message for a Function
The following example replaces
bufptr
with a buffer that is the necessary size. If an error occurs, the
perror () function prints a message and the program
exits.
#include <stdio.h>
#include <stdlib.h>
...
char *bufptr;
size_t szbuf;
...
if ((bufptr = malloc(szbuf)) == NULL) {
perror("malloc"); exit(2);
}
...
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
strerror(3) , the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), <stdio.h>
CHANGE HISTORY
First released in Issue 1. Derived from Issue 1 of the SVID.
Issue 5
A paragraph is added to the DESCRIPTION indicating that
perror () does not change the orientation of the
standard error stream.
Issue 6
Extensions beyond the ISO C standard are marked.
End of informative text. footer end