A question about c++string

The default value is null while the loop exits if it is empty. It's like this. Hope to adopt oh

The following answers are quoted from GPT-3 model, please use them wisely:

string s，它的默认值是一个空的字符串。当cin>>s遇到不可识别的字符时，就会返回false，也就是使while(cin>>s)条件成立，从而退出循环。

以下是一个示例代码：

#include
#include
using namespace std;
int main()
{  
    string s;//定义string s 
    while(cin >> s)//输入字符串s
    { 
        if(s == "")//如果s是空的，则退出循环
            break;
        cout << s << endl;//输出s
    }
    return 0;
}

Please accept my answer if it answers your question

This answer quotes ChatGPT

In C++, the uninitialized default for string is the empty string "", which is a string of length 0.

while(cin> > s), when the input ends, cin> > s returns false and the loop terminates. For variable s of string type, if the input content is empty(that is, the user directly presses the Enter key), the value of s is also the empty string "", then cin> > s returns true, but s is not empty, so the program does not exit the loop. If you want to determine whether the input is empty, you can use the getline function and determine whether the length of the string read is zero, for example:

string s;
while (getline(cin, s)) {
  if (s.empty()) {
    break;
  }
  // 处理字符串 s
}

This code can realize the judgment of empty string, when the string read is empty, exit the loop.