Question

我正在创建一个程序，其中基本上要求用户提供三个值，程序将接受这些值，然后将它们输入到二次公式中。我得到了二次公式，一切都有效。唯一的问题是，无论我作为用户输入放置是否重复该程序，它只是直接开始。我不能退出该计划。我一直在寻找解决方案，但没有雪茄。我应该提一下，我在编程方面没有那么多经验。但我会试着去理解我做错了什么。任何帮助都是很好的帮助

    int main()
    {
        //variables
        double a;
        double b;
        double c;
        double x1;
        double x2;
        double discriminant;
        char exeAgain='n';

        do
        {
          cout<<"Please enter a value for A, B, and C to be used in the quadratic formula (and then press 'enter'): "<<endl;
          cin>>a>>b>>c; //gets the values for A, B, and C

            //the equations for the quadratic formula
           discriminant=(b*b-(4*a*c));
           x1= (-1*b + (sqrt(discriminant)))/(2*a);
           x2= (-1*b - (sqrt(discriminant)))/(2*a);

            if(discriminant>0) //if inside the sqrt is more than 0 (desired)
            {
                cout<<"The roots of " <<a<< "x^2 + " <<b<< "x + " <<c<< " is/are: " <<endl;
                cout<<x1<<" and "<<x2<<endl;
            }

            else if(discriminant==0) //if inside the sqrt is 0
            {
                cout<<"The roots of " <<a<< "x^2 + " <<b<< "x + " <<c<< " is " <<endl;
                cout<<x1<<endl;
            }

            else //the discriminant is less than 0 (leads to complex roots)
            {
                discriminant = -1 * discriminant; //used to change the discriminant to a positive # 
                cout<<"The roots of " <<a<< "x^2 + " <<b<< "x + " <<c<< " is/are: " <<endl;
                cout<<"("<<(-1*b)<<" + "<<sqrt(discriminant)<<"i)/"<<2*a<<" and ("<<(-1*b)<<" - "<<sqrt(discriminant)<<"i)/"<<2*a<<endl;

            } 
               cout<<"Would you like to execute this program again? Type in Y or y for yes, or any other letter to quit the program: ";
               cin>>exeAgain;

     } while(exeAgain == 'y' || exeAgain == 'Y');
         return 0;  
    }

Answer 1

你正在进行OR ||检查。你的第二个条件总是评估为真。

将其更改为：

while(exeAgain == 'y' || exeAgain == 'Y');

Answer 2

使用exeAgain != 'y' || exeAgain != 'Y'。

当前表达式exeAgain != 'y' || 'Y'表示“exeAgain与'y'不同，或'Y'不为零。由于'Y'是一个不等于零的文字常量，循环总是重复。

要求用户输入以重新运行程序或退出

2 个答案: