带终止字符C++切换情况计算器

Question

我正在尝试制作一个开关实例计算器，它将要求一个表达式（例如2+2)并打印答案，重复这个过程直到用户输入'q'。

int main() {

double operand1;
double operand2;
char operation;
double answer;

while (operation != 'q'){

cout << "Enter an expression:""\n";
cin >> operand1 >> operation >> operand2;


     switch(operation)
{
    case '+':
        answer = (operand1 + operand2);
        break;

    case '-':
        answer = (operand1 - operand2);
        break;

    case '*':
        answer = (operand1 * operand2);
        break;

    case '/':
        answer = (operand1 / operand2);
        break;


    default:
            cout << "Not an operation :/";
            return 0;

}

    cout <<operand1<<operation<<operand2<< "=" << answer<< endl;

}
 return 0;
}

Answer 1

由于您正在一次读取3个变量，当您在控制台中键入q时，它将被分配给operand1，而不是operation，后者是while循环的终止符-因此，将启动无限循环。

基本问题是应用程序的逻辑。该代码的最快解析如下：

int main() {

    double operand1;
    double operand2;
    char operation;
    char more = 'y';
    double answer;

    while (more != 'n') {

        cout << "Enter an expression:""\n";
        cin >> operand1 >> operation >> operand2;

        switch (operation)
        {
        case '+':
            answer = (operand1 + operand2);
            break;

        case '-':
            answer = (operand1 - operand2);
            break;

        case '*':
            answer = (operand1 * operand2);
            break;

        case '/':
            answer = (operand1 / operand2);
            break;


        default:
            cout << "Not an operation :/";
            return 0;

        }

        cout << operand1 << operation << operand2 << "=" << answer << endl;
        cout << "Continue? (y/n) ";
        cin >> more;
    }
    return 0;
}