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strspn, wcsspn, _mbsspn, _mbsspn_l

Returns the index of the first character in a string that doesn't belong to a specified set of characters.


_mbsspn and _mbsspn_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.


size_t strspn(
   const char *str,
   const char *strCharSet
size_t wcsspn(
   const wchar_t *str,
   const wchar_t *strCharSet
size_t _mbsspn(
   const unsigned char *str,
   const unsigned char *strCharSet
size_t _mbsspn_l(
   const unsigned char *str,
   const unsigned char *strCharSet,
   _locale_t locale


Null-terminated string to search.

Null-terminated character set.

Locale to use.

Return value

Returns an integer value specifying the length of the substring in str that consists entirely of characters in strCharSet. If str begins with a character not in strCharSet, the function returns 0.


The strspn function returns the index of the first character in str that doesn't belong to the set of characters in strCharSet. The search doesn't include terminating null characters.

wcsspn and _mbsspn are wide-character and multibyte-character versions of strspn. The arguments of wcsspn are wide-character strings. The arguments of _mbsspn are multibyte-character strings. _mbsspn validates its parameters. If str or strCharSet is NULL, the invalid parameter handler is invoked, as described in Parameter validation . If execution is allowed to continue, _mbspn sets errno to EINVAL and returns 0. strspn and wcsspn don't validate their parameters. These three functions behave identically otherwise.

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 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.

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
_tcsspn strspn _mbsspn wcsspn
n/a n/a _mbsspn_l n/a


Routine Required header
strspn <string.h>
wcsspn <string.h> or <wchar.h>
_mbsspn, _mbsspn_l <mbstring.h>

For more compatibility information, see Compatibility.


// crt_strspn.c
// This program uses strspn to determine
// the length of the segment in the string "cabbage"
// consisting of a's, b's, and c's. In other words,
// it finds the first non-abc letter.

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

int main( void )
   char string[] = "cabbage";
   int  result;
   result = strspn( string, "abc" );
   printf( "The portion of '%s' containing only a, b, or c "
           "is %d bytes long\n", string, result );
The portion of 'cabbage' containing only a, b, or c is 5 bytes long

See also

String manipulation
Interpretation of multibyte-character sequences
_strspnp, _wcsspnp, _mbsspnp, _mbsspnp_l
strcspn, wcscspn, _mbscspn, _mbscspn_l
strncat, _strncat_l, wcsncat, _wcsncat_l, _mbsncat, _mbsncat_l
strncmp, wcsncmp, _mbsncmp, _mbsncmp_l
strncpy, _strncpy_l, wcsncpy, _wcsncpy_l, _mbsncpy, _mbsncpy_l
_strnicmp, _wcsnicmp, _mbsnicmp, _strnicmp_l, _wcsnicmp_l, _mbsnicmp_l
strrchr, wcsrchr, _mbsrchr, _mbsrchr_l