_strset, _strset_l, _wcsset, _wcsset_l, _mbsset, _mbsset_l

Sets characters of a string to a character. More secure versions of these functions are available; see _strset_s, _strset_s_l, _wcsset_s, _wcsset_s_l, _mbsset_s, _mbsset_s_l.


_mbsset and _mbsset_l cannot be used in applications that execute in the Windows Runtime. For more information, see CRT functions not supported in Universal Windows Platform apps.


char *_strset(
   char *str,
   int c
char *_strset_l(
   char *str,
   int c,
   _locale_t locale
wchar_t *_wcsset(
   wchar_t *str,
   wchar_t c
wchar_t *_wcsset_l(
   wchar_t *str,
   wchar_t c,
   _locale_t locale
unsigned char *_mbsset(
   unsigned char *str,
   unsigned int c
unsigned char *_mbsset_l(
   unsigned char *str,
   unsigned int c,
   _locale_t locale


Null-terminated string to be set.

Character setting.

Locale to use.

Return value

Returns a pointer to the altered string.


The _strset function sets all characters (except the terminating null character) of str to c, converted to char. _wcsset and _mbsset_l are wide-character and multibyte-character versions of _strset, and the data types of the arguments and return values vary accordingly. These functions behave identically otherwise.

_mbsset validates its parameters. If str is a null pointer, the invalid parameter handler is invoked, as described in Parameter validation. If execution is allowed to continue, _mbsset returns NULL and sets errno to EINVAL. _strset and _wcsset don't validate their parameters.

The output value is affected by the setting of the LC_CTYPE category setting of the locale. For more information, see setlocale. The versions of these functions are identical, except that the ones that don't have the _l suffix use the current locale and the ones that do have the _l suffix instead use the locale parameter that's passed in. For more information, see Locale.


These functions might be vulnerable to buffer overrun threats. Buffer overruns can be used for system attacks because they can cause an unwarranted elevation of privilege. For more information, see Avoiding buffer overruns.

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
_tcsset _strset _mbsset _wcsset
_tcsset_l _strset_l _mbsset_l _wcsset_l


Routine Required header
_strset <string.h>
_strset_l <tchar.h>
_wcsset <string.h> or <wchar.h>
_wcsset_l <tchar.h>
_mbsset, _mbsset_l <mbstring.h>

For more compatibility information, see Compatibility.


// crt_strset.c
// compile with: /W3

#include <string.h>
#include <stdio.h>

int main( void )
   char string[] = "Fill the string with something.";
   printf( "Before: %s\n", string );
   _strset( string, '*' ); // C4996
   // Note: _strset is deprecated; consider using _strset_s instead
   printf( "After:  %s\n", string );
Before: Fill the string with something.
After:  *******************************

See also

String manipulation
Interpretation of multibyte-character sequences
_mbsnbset, _mbsnbset_l
memset, wmemset
strcat, wcscat, _mbscat
strcmp, wcscmp, _mbscmp
strcpy, wcscpy, _mbscpy
_strnset, _strnset_l, _wcsnset, _wcsnset_l, _mbsnset, _mbsnset_l