仰视源代码，实现strcmp

//这是系统库的实现
int strcmp(const char* src, const char* dest)
{
	int rtn = 0;
	while(!(rtn = *(unsigned char*)src - *(unsigned char*)dest) && *dest)
	{
		++src;
		++dest;
	}
	if (rtn < 0)
	{
		rtn = -1;
	}else if (rtn > 0)
	{
		rtn = 1;
	}
	return rtn;
}