输入string对象的序列知道相同的单词

#include <iostream>
#include <string>
using namespace std;

int main()
{
	//输入string对象的序列知道相同的单词或者读完 
	string str,last_str;
	cout<<"Enter your string :"<<endl;
	bool flag=false;
	while(cin>>str)
	{
		if(str==last_str)
		{
			flag=true;//用flag判断是因为while结束后str一定等于last—str 
			break;
		}			
		else
			last_str=str;
	}
	if(flag) 
		cout<<"the repeat word is : "<<str<<endl;
	else
		cout<<"No word is repeated!"<<endl;
	
	return 0;
}