strerror, _strerror, _wcserror, __wcserror
Gets a system error message string (strerror, _wcserror) or formats a user-supplied error message string (_strerror, __wcserror). More secure versions of these functions are available; see strerror_s, _strerror_s, _wcserror_s, __wcserror_s.
Syntax
char * strerror(
int errnum );
char * _strerror(
const char *strErrMsg );
wchar_t * _wcserror(
int errnum );
wchar_t * __wcserror(
const wchar_t *strErrMsg );
Parameters
errnum
Error number.
strErrMsg
User-supplied message.
Return value
All of these functions return a pointer to an error-message string, in a thread-local storage buffer owned by the runtime. Later calls on the same thread can overwrite this string.
Remarks
The strerror function maps errnum to an error-message string and returns a pointer to the string. The strerror and _strerror functions don't actually print the message. To print, call an output function such as fprintf:
if (( _access( "datafile", 2 )) == -1 )
fprintf( stderr, _strerror(NULL) );
If strErrMsg is passed as NULL, _strerror returns a pointer to a string. It contains the system error message for the last library call that produced an error. If you call __wcserror, the error-message string is terminated by the newline character ('\n'). The other functions don't add '\n'. When strErrMsg isn't NULL, the string contains, in order: your strErrMsg string, a colon, a space, the system error message. Your string message can be, at most, 94 characters long, in either narrow (_strerror) or wide (__wcserror) characters.
The actual error number for _strerror is stored in the variable errno. To produce accurate results, call _strerror immediately after a library routine returns an error. Otherwise, later calls to library routines may overwrite the errno value.
_wcserror and __wcserror are wide-character versions of strerror and _strerror, respectively.
_strerror, _wcserror, and __wcserror are Microsoft-specific, not part of the Standard C library. We don't recommend you use them where you want portable code. For Standard C compatibility, use strerror instead.
To get error strings, we recommend strerror or _wcserror instead of the deprecated macros _sys_errlist and _sys_nerr and the deprecated internal functions __sys_errlist and __sys_nerr.
By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.
Generic-text routine mappings
| TCHAR.H routine | _UNICODE and _MBCS not defined |
_MBCS defined |
_UNICODE defined |
|---|---|---|---|
_tcserror |
strerror |
strerror |
_wcserror |
Requirements
| Routine | Required header |
|---|---|
strerror |
<string.h> |
_strerror |
<string.h> |
_wcserror, __wcserror |
<string.h> |
For more compatibility information, see Compatibility.
Example
See the example for perror.