我的节目中我做错了什么？ [英] What am I doing wrong in my program?

问题描述

int main(int argc, char** argv) 
{
    string stopLightColor = "" ;
    cout << "Please enter what your stoplight color is: " << endl ;
    cin >> stopLightColor;
    if (stopLightColor == "red" || "yellow") {
        cout << "Please stop." << endl ;
    }
    else if (stopLightColor == "green") 
    {
        cout << "Continue" << endl ;
    }

    return 0 ;
}

无论我输入什么，答案总是请停止。



我尝试了什么：



我没有尝试任何新的东西，因为我不喜欢知道我能解决的问题。

No matter what I type in, the answer always is "Please stop."

What I have tried:

I haven't necessarily tried anything new because I don't know what I could fix about it.

推荐答案

引用：

什么是我在程序中做错了吗？

What am I doing wrong in my program?

因为你不知道C ++语法。

通过阅读文档和跟随tutos来学习C ++。

特别注意逻辑运算符。

Because you don't know the C++ syntax.
Learn really C++ by reading documentation and follow tutos.
Pay particular attention to logical operators.

正如其他人已经建议你误解了条件表达式在C ++中是如何工作的。也就是说，我想有办法改进你的代码。我想有两种情况：



（1）您信任信号量（用户输入）到是'红色'或'黄色'或'绿色'。

在这种情况下，代码可以简单写一下

As others already suggested you misunderstood how conditional expressions works in C++. That said, I suppose there ways to improve your code. I suppose there are two scenarios:

(1) You trust the semaphore (the user input) to be either 'red' or 'yellow' or 'green'.
In such scenario, the code could be written simply

if (stopLightColor == "green")
{
  cout << "Continue" << endl;
}
else // it IS either 'red' or 'yellow', don't bother to check
{
  cout << "Please stop" << endl;
}

（2）您允许信号量（用户输入）有时会被打破。

在这种情况下你必须处理'破碎的'可能性。

(2) You allow the semaphore (the user input) to be broken, at times.
In such a scenario you HAVE to handle the 'broken' eventuality.

if (stopLightColor == "green")
{
  cout << "Continue" << endl;
}
else if ( stopLightColor == "yellow" || stopLightColor == "red")
{
  cout << "Please stop" << endl;
}
else // the semaphore is broken
{
  cout << "Warning: the semaphore is broken, please go on very carefully" << endl;
}

正如ppolymorphe建议的那样，看看这一行

As ppolymorphe has suggested, look at this line

if (stopLightColor == "red" || "yellow")

你能想到它的正确方法吗？写的？

can you think of the correct way it should be written ?

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