我不完全明白为什么我的 while 循环没有捕捉到任何这些条件

Question

我正在尝试反向输出输入字符串，当用户输入“done”、“Done”或“d”时它将停止。这样，while 循环就不会捕获任何这些条件来停止循环。

#include`<iostream>
using namespace std;

int main() {

   string userInput;
   int i;
   char output;
   getline(cin, userInput);

    
    
      while (userInput != "done" || userInput != "Done" || userInput != "d") {
        for (i = userInput.size() - 1; i >= 0; --i) {
            output = userInput.at(i);
            cout << output;
        }
        cout << endl;
        getline(cin, userInput);
    } 
   

   return 0;
}

Answer 1

替换

while (userInput != "done" || userInput != "Done" || userInput != "d")

和

while ( ! (userInput == "done" || userInput == "Done" || userInput == "d") )

我不完全明白为什么我的 while 循环没有捕捉到任何这些条件

I don't exactly understand why my while loop is not catching any of these conditions

c++

reverse

loops

while-loop