memcpy_s, wmemcpy_s
Copies bytes between buffers. These are versions of memcpy, wmemcpy with security enhancements as described in Security Enhancements in the CRT.
errno_t memcpy_s( void *dest, size_t numberOfElements, const void *src, size_t count ); errno_t wmemcpy_s( wchar_t *dest, size_t numberOfElements, const wchar_t *src, size_t count );
Parameters
- dest
-
New buffer.
- numberOfElements
-
Size of the destination buffer.
- src
-
Buffer to copy from.
- count
-
Number of characters to copy.
memcpy_s copies count bytes from src to dest; wmemcpy_s copies count wide characters (two bytes). If the source and destination overlap, the behavior of memcpy_s is undefined. Use memmove_s to handle overlapping regions.
These functions validate their parameters. If dest or src is a null pointer, or numberOfElements is too small for the buffer, these functions invoke the invalid parameter handler, as described in Parameter Validation . If execution is allowed to continue, these functions return EINVAL and set errno to EINVAL.
| Routine | Required header | Compatibility |
|---|---|---|
| memcpy_s | <memory.h> or <string.h> | Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition, Windows NT 4.0, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 |
| wmemcpy_s | <wchar.h> | Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition, Windows NT 4.0, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 |
For additional compatibility information, see Compatibility in the Introduction.
// crt_memcpy_s.c
// Copy memory in a more secure way.
#include <memory.h>
#include <stdio.h>
int main()
{
int a1[10], a2[100], i;
errno_t err;
// Populate a2 with squares of integers
for (i = 0; i < 100; i++)
{
a2[i] = i*i;
}
// Tell memcpy_s to copy 10 ints (40 bytes), giving
// the size of the a1 array (also 40 bytes).
err = memcpy_s(a1, sizeof(a1), a2, 10 * sizeof (int) );
if (err)
{
printf("Error executing memcpy_s.\n");
}
else
{
for (i = 0; i < 10; i++)
printf("%d ", a1[i]);
}
printf("\n");
}
Output
0 1 4 9 16 25 36 49 64 81
Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
