#include <iostream>

#include <string.h>

using namespace std;

void* memmove(void *dst, const void *src, size_t count){

	// 容错处理

	if (dst == NULL || src == NULL){

		return NULL;

	}

	unsigned char *pdst = (unsigned char *)dst;

	const unsigned char *psrc = (const unsigned char *)src;

	//推断内存是否重叠

	bool flag1 = (pdst >= psrc && pdst < psrc + count);

	bool flag2 = (psrc >= pdst && psrc < pdst + count);

	if (flag1 || flag2){

		// 倒序拷贝

		while (count){

			*(pdst + count - 1) = *(psrc + count - 1);

			count--;

		}//while

	}

	else{

		// 拷贝

		while (count--){

			*pdst = *psrc;

			pdst++;

			psrc++;

		}//while

	}

	return dst;

}