#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
//模拟memcpy
void my_momcpy(char *dest, const char *str, int count)
{
assert(dest != NULL);
assert(str != NULL);
char *ret = dest;
int i = 0;
for (i = 0; i < count; i++)
{
*dest++ = *str++;
}
}
int main()
{
char a[100] = "abcdef" ;
my_momcpy(a + 1, a + 2, 2);
printf( "%s\n", a);
system( "pause");
return 0;
}
/* MEMCPY.C: Illustrate overlapping copy: memmove
* handles it correctly; memcpy does not.
*/
#include <memory.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
char string1[60] = "The quick brown dog jumps over the lazy fox" ;
char string2[60] = "The quick brown fox jumps over the lazy dog" ;
/* 1 2 3 4 5
* 12345678901234567890123456789012345678901234567890
*/
void main(void )
{
printf( "\t\t%s\n", string1);
printf( "\t\t%s\n", string2);
printf( "Function:\tmemcpy without overlap\n" );
printf( "Source:\t\t%s\n", string1 + 40);
printf( "Destination:\t%s\n", string1 + 16);
memcpy(string1 + 16, string1 + 40, 3);
printf( "Result:\t\t%s\n", string1);
printf( "Length:\t\t%d characters\n\n" , strlen(string1));
/* Restore string1 to original contents */
memcpy(string1 + 16, string2 + 40, 3);
printf( "Function:\tmemmove with overlap\n" );
printf( "Source:\t\t%s\n", string2 + 4);
printf( "Destination:\t%s\n", string2 + 10);
memmove(string2 + 10, string2 + 4, 40);
printf( "Result:\t\t%s\n", string2);
printf( "Length:\t\t%d characters\n\n" , strlen(string2));
printf( "Function:\tmemcpy with overlap\n" );
printf( "Source:\t\t%s\n", string1 + 4);
printf( "Destination:\t%s\n", string1 + 10);
memcpy(string1 + 10, string1 + 4, 40);
printf( "Result:\t\t%s\n", string1);
printf( "Length:\t\t%d characters\n\n" , strlen(string1));
system( "pause");
}
原文：http://10626786.blog.51cto.com/10616786/1693366