_mbsnbcpy_s, _mbsnbcpy_s_l

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06/05/2017

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The latest version of this topic can be found at _mbsnbcpy_s, _mbsnbcpy_s_l.

Copies n bytes of a string to a destination string. These versions of _mbsnbcpy, _mbsnbcpy_l have security enhancements, as described in Security Features in the CRT.

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

errno_t _mbsnbcpy_s(  
   unsigned char * strDest,  
   size_t sizeInBytes,  
   const unsigned char * strSource,  
   size_t count   
);  
errno_t _mbsnbcpy_s_l(  
   unsigned char * strDest,  
   size_t sizeInBytes,  
   const unsigned char * strSource,  
   size_t count,  
   _locale_t locale  
);  
template <size_t size>  
errno_t _mbsnbcpy_s(  
   unsigned char (&strDest)[size],  
   const unsigned char * strSource,  
   size_t count   
); // C++ only  
template <size_t size>  
errno_t _mbsnbcpy_s_l(  
   unsigned char (&strDest)[size],  
   const unsigned char * strSource,  
   size_t count,  
   _locale_t locale  
); // C++ only

Parameters

strDest
Destination for character string to be copied.

sizeInBytes
Destination buffer size.

strSource
Character string to be copied.

count
Number of bytes to be copied.

locale
Locale to use.

Return Value

Zero if successful; EINVAL if a bad parameter was passed in.

Remarks

The _mbsnbcpy_s function copies count bytes from strSource to strDest. If count exceeds the size of strDest, either of the input strings is a null pointer, or sizeInBytes or count is 0, the function invokes the invalid parameter handler as described in Parameter Validation . If execution is allowed to continue, the function returns EINVAL. If the source and destination strings overlap, the behavior of _mbsnbcpy_s is undefined.

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.

Note

Unlike the non-secure version of this function, _mbsnbcpy_s does not do any null padding and always null terminates the string.

In C++, using these functions is simplified by template overloads; the overloads can infer buffer length automatically (eliminating the need to specify a size argument) and they can automatically replace older, non-secure functions with their newer, secure counterparts. For more information, see Secure Template Overloads.

The debug versions of these functions first fill the buffer with 0xFD. To disable this behavior, use _CrtSetDebugFillThreshold.

Generic-Text Routine Mappings

Tchar.h routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
`_tcsncpy_s`	`_strncpy_s`	`_mbsnbcpy_s`	`_wcsncpy_s`
`_tcsncpy_s_l`	`_strncpy_s_l`	`_mbsnbcpy_s_l`	`_wcsncpy_s_l`

Requirements

Routine	Required header
`_mbsnbcpy_s`	<mbstring.h>
`_mbsnbcpy_s_l`	<mbstring.h>

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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