//模拟实现memmove函数（考虑内存重叠）

#include <stdio.h>

#include <assert.h>

#include <string.h>

void * memmove(void * dst, const void * src, int count)

{

	void * ret = dst;

	assert(dst);

	assert(src);

	if (dst <= src || (char *)dst >= ((char *)src + count))   //正常情况不发生重叠，从低到高

	{

		while (count--)

		{

			*(char *)dst = *(char *)src;

			dst = (char *)dst + 1;

			src = (char *)src + 1;

		}

	}

	else                                                      //发生重叠，从低到高

	{

		dst = (char *)dst + count - 1;

		src = (char *)src + count - 1;

		while (count--)

		{

			*(char *)dst = *(char *)src;

			dst = (char *)dst - 1;

			src = (char *)src - 1;

		}

	}

	return ret;

}

int main()

{

	char p[] = "hello!";

	char *q = "world";

	memmove(p, q,strlen(q)+1 );

	printf("%s\n", p);

	return 0;

}