_strset, _strset_l, _wcsset, _wcsset_l, _mbsset, _mbsset_l
Collapse the table of content
Expand the table of content
Important This document may not represent best practices for current development, links to downloads and other resources may no longer be valid. Current recommended version can be found here. ArchiveDisclaimer

_strset, _strset_l, _wcsset, _wcsset_l, _mbsset, _mbsset_l

Set 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.

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.

Returns a pointer to the altered string.

The _strset function sets all the characters of str to c (converted to char), except the terminating null character. _wcsset and _mbsset_l are wide-character and multibyte-character versions of _strset. 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 for more information. The versions of these functions without the _l suffix use the current locale for this locale-dependent behavior; the versions with the _l suffix are identical except that they use the locale parameter passed in instead. For more information, see Locale.

Security Note    These functions incur a potential threat brought about by a buffer overrun problem. Buffer overrun problems are a frequent method of system attack, resulting in 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










Required header






<string.h> or <wchar.h>



_mbsset, _mbsset_l


For additional compatibility information, see Compatibility in the Introduction.

// 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: *******************************

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

© 2015 Microsoft