strspn, wcsspn, _mbsspn, _mbsspn_l

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06/05/2017

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Returns the index of the first character, in a string, that does not belong to a set of characters.

Important

_mbsspn and _mbsspn_l cannot be used in applications that execute in the Windows Runtime. For more information, see CRT functions not supported with /ZW.

Syntax

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  
);

Parameters

str
Null-terminated string to search.

strCharSet
Null-terminated character set.

locale
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.

Remarks

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

wcsspn and _mbsspn are wide-character and multibyte-character versions of strspn. The arguments of wcsspn are wide-character strings; those of _mbsspn are multibyte-character strings. _mbsspn validates its parameters. If str or strCharSet isNULL, 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 do not 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; 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.

Generic-Text Routine Mappings

TCHAR.H routine	_UNICODE & _MBCS not defined	_MBCS defined	_UNICODE defined
`_tcsspn`	`strspn`	`_mbsspn`	`wcsspn`
n/a	n/a	`_mbsspn_l`	n/a

Requirements

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

For additional compatibility information, see Compatibility.

Example

// 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

.NET Framework Equivalent

System::String::Substring

共用方式為