C++ 中如何判断cin输入流的结尾-PHP中文网问答

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C++ 中如何判断cin输入流的结尾

大家讲道理 2017-04-17 11:08:08

[C++讨论组]

484

string tmp;
while(1)
{
cin >> tmp;
if(tmp[0] == '\0')
break;
cout << "输出字符：" << tmp << endl;
}

我使用了 cin.eof() 和 cin.good() 都不可以，在win7平台下，mingw编译我刚刚开始学习C++，希望高人帮帮忙

原来是我自己的思路想错了，不能直接判断cin是否到结尾，应该输入Ctrl+z 再按回车，这样就能退出了

大家讲道理

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全部回复(2)

巴扎黑2017-04-17 11:10:08 2楼

#include <iostream>
#include <string>
using namespace std;
int main(){
        string tmp = "";
        while(cin >> tmp){
                cout << "输出字符：" << tmp << endl;
        }
        return 0;
}

Here the expression cin >> x performs an input operation that might update x, and as its expression result returns a reference to the stream, i.e. to cin. So cin is being used directly as a condition. That invokes a conversion to boolean, which is defined such that it on its own is equivalent to !cin.fail() (i.e., the expression cin >> x as condition is equivalent to writing !(cin >> x).fail() or, as a comma expression, (cin >> x, !cin.fail())).

http://stackoverflow.com/questions/13343991/c-why-cin-eof-read-last-char-twice