_strset, _strset_l, _wcsset, _wcsset_l, _mbsset, _mbsset_l


The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.

The latest version of this topic can be found at _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 with /ZW.


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 do not validate their parameters.

The output value is affected by the setting of the LC_CTYPE category setting of the locale; see setlocale, _wsetlocale for more information. 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.

Generic-Text Routine Mappings

TCHAR.H routine _UNICODE & _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 additional 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:  *******************************  

.NET Framework Equivalent

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.

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