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| #include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
void mymemcpy(void * dest, const void * src, size_t len)
{
assert((dest != NULL) && (src != NULL));
char * pdest = (char *) dest;
const char * psrc = (const char *) src;
if (pdest > psrc && pdest < psrc + len) {
for (size_t i = len - 1; i != -1; --i)
pdest[i] = psrc[i];
}
else {
while(len--)
*pdest++ = *psrc++;
}
}
int main()
{
const char a[] = "hello world";
void *dest = malloc(23);
mymemcpy(dest, a, 5);
printf("dest is %s\n", dest);
mymemcpy(dest+1, dest, 5);
printf("dest is %s\n", dest);
free(dest);
return 0;
}
|