本题不需要那么复杂，直接将find的返回值转int，判断是否为-1即可

核心代码如下

	if((int)s1.find(s2)!=-1)
	{
		cout<<s2<<" is substring of "<<s1;
	}
	else if((int)s2.find(s1)!=-1)
	{
		cout<<s1<<" is substring of "<<s2;
	}