_ismbslead, _ismbstrail, _ismbslead_l, _ismbstrail_l

项目
06/05/2017

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The latest version of this topic can be found at _ismbslead, _ismbstrail, _ismbslead_l, _ismbstrail_l.

Performs context-sensitive tests for multibyte-character-string lead bytes and trail bytes and determines whether a given substring pointer points to a lead byte or a trail byte.

Important

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

Syntax

int _ismbslead(  
   const unsigned char *str,  
   const unsigned char *current   
);  
int _ismbstrail(  
   const unsigned char *str,  
   const unsigned char *current   
);  
int _ismbslead_l(  
   const unsigned char *str,  
   const unsigned char *current,  
   _locale_t locale  
);  
int _ismbstrail_l(  
   const unsigned char *str,  
   const unsigned char *current,  
   _locale_t locale  
);

Parameters

str
Pointer to the start of the string or the previous known lead byte.

current
Pointer to the position in the string to be tested.

locale
The locale to use.

Return Value

_ismbslead returns –1 if the character is a lead byte and _ismbstrail returns –1 if the character is a trail byte. If the input strings are valid but are not a lead byte or trail byte, these functions return zero. If either argument is NULL, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, these functions return NULL and set errno to EINVAL.

Remarks

_ismbslead and _ismbstrail are slower than the _ismbblead and _ismbbtrail versions because they take the string context into account.

The versions of these functions that have the _l suffix are identical except that for their locale-dependent behavior they use the locale that's passed in instead of the current locale. For more information, see Locale.

Requirements

Routine	Required header	Optional header
`_ismbslead`	<mbctype.h> or <mbstring.h>	<ctype.h>,* <limits.h>, <stdlib.h>
`_ismbstrail`	<mbctype.h> or <mbstring.h>	<ctype.h>,* <limits.h>, <stdlib.h>
`_ismbslead_l`	<mbctype.h> or <mbstring.h>	<ctype.h>,* <limits.h>, <stdlib.h>
`_ismbstrail_l`	<mbctype.h> or <mbstring.h>	<ctype.h>,* <limits.h>, <stdlib.h>

* For manifest constants for the test conditions.

For more compatibility information, see Compatibility.

.NET Framework Equivalent

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

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