#include <stdio.h> #include <stdlib.h> char * mymemcpy(char* dest, char* source, size_t count); int main(void) { char str[] = "0123456789"; mymemcpy( str+3, str+1, 5 ); printf("here is : %s",str); return 0; } char* mymemcpy(char* dest, char* source, size_t count) { char* ret = dest; if (ret <= source || ret >= (source + count)) { while (count --) *dest++ = *source++; } else { dest += count - 1; source += count - 1; while (count--) *dest-- = *source--; } return ret; }
