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memmove_s, wmemmove_s

 

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The latest version of this topic can be found at memmove_s, wmemmove_s.

Moves one buffer to another. These are versions of memmove, wmemmove with security enhancements as described in Security Features in the CRT.

Syntax

  
      errno_t memmove_s(  
   void *dest,  
   size_t numberOfElements,  
   const void *src,  
   size_t count  
);  
errno_t wmemmove_s(  
   wchar_t *dest,  
   size_t numberOfElements,  
   const wchar_t *src,  
   size_t count  
);  

Parameters

dest
Destination object.

numberOfElements
Size of the destination buffer.

src
Source object.

count
Number of bytes (memmove_s) or characters (wmemmove_s) to copy.

Return Value

Zero if successful; an error code on failure

Error Conditions

dest numberOfElements src Return value Contents of dest
NULL any any EINVAL not modified
any any NULL EINVAL not modified
any < count any ERANGE not modified

Remarks

Copies count bytes of characters from src to dest. If some regions of the source area and the destination overlap, memmove_s ensures that the original source bytes in the overlapping region are copied before being overwritten.

If dest or if src is a null pointer, or if the destination string is too small, these functions invoke an invalid parameter handler, as described in Parameter Validation . If execution is allowed to continue, these functions return EINVAL and set errno to EINVAL.

Requirements

Routine Required header
memmove_s <string.h>
wmemmove_s <wchar.h>

For additional compatibility information, see Compatibility in the Introduction.

Example

// crt_memmove_s.c  
//  
// The program demonstrates the   
// memmove_s function which works as expected  
// for moving overlapping regions.  
  
#include <stdio.h>  
#include <string.h>  
  
int main()  
{  
   char str[] = "0123456789";  
  
   printf("Before: %s\n", str);  
  
   // Move six bytes from the start of the string  
   // to a new position shifted by one byte. To protect against  
   // buffer overrun, the secure version of memmove requires the  
   // the length of the destination string to be specified.   
  
   memmove_s((str + 1), strnlen(str + 1, 10), str, 6);   
  
   printf_s(" After: %s\n", str);  
}  

Output

Before: 0123456789  
 After: 0012345789  

.NET Framework Equivalent

System::Buffer::BlockCopy

See Also

Buffer Manipulation
_memccpy
memcpy, wmemcpy
strcpy_s, wcscpy_s, _mbscpy_s
strcpy, wcscpy, _mbscpy
strncpy_s, _strncpy_s_l, wcsncpy_s, _wcsncpy_s_l, _mbsncpy_s, _mbsncpy_s_l
strncpy, _strncpy_l, wcsncpy, _wcsncpy_l, _mbsncpy, _mbsncpy_l