Question

我最近开始研究C ++，并且尝试通过一些操作来创建“计算器”。但是我陷入了字符串26（cin >> select;），这似乎没有响应。为什么？

//CALCULATOR
#include <iostream>
using namespace std;

int main()
{
int start;
int choose;

int first;
int second;
int unic;

int result;

cout << "CALCULATOR (2 values)" << endl;
cout << "Click a botton to continue: " << endl;
cin >> start;
cout << "Write: " << endl;
cout << "- '1' for sum" << endl;
cout << "- '2' for subtraction" << endl;
cout << "- '3' for moltiplication" << endl;
cout << "- '4' for power of 2" << endl;

cout << "Your answer: " << endl;
cin >> choose;
cout << "________________________" << endl;

{ 
        if (choose=1, 2, 3)
        cout << "Insert the first value: " << endl;
        cin >> first;
        cout << "Insert the second value: " << endl;
        cin >> second;

    { 
        if (choose=1)
        result = first + second;
    }

    { 
        if (choose=2)
        result = first + second;
    }

    { 
        if (choose=3)
        result = first * second;
    
}

{ 
    if (choose=4)
    cout << "Insert the value: " << endl;
    cin >> unic;
    result = unic * unic;
}
}

cout << "Your result is: " << result;
}

它没有给我任何错误，但是它继续执行我编写的所有“ cout”操作，而没有给我用“ cin”编写值的可能性。

Answer 1

您的代码中有几个问题，

在C ++中，=代表您必须使用==

    if (choose = 1, 2, 3){
       ...
    // this doesn't work in C/C++
    // change it into 
    if (choose == 1 || choose == 2 || choose == 3)

在条件（如果/否则或循环/同时）下有多行代码时，您将需要在花括号内显式阻止它们。因此，如果先阻止到此，则情况会发生变化

 if (choose == 1 || choose == 2 || choose == 3){
     cout << "Insert the first value: " << endl;
     cin >> first;
     cout << "Insert the second value: " << endl;
     cin >> second;
     ...

嵌套if条件相同。
也没有理由接受输入。
如果您修复了所有错误，则应该获得如下代码->

    //CALCULATOR
    #include <iostream>
    
    using namespace std;
    
    int main()
    {
        int start;
        int choose;
    
        int first;
        int second;
        int unic;
    
        int result;
    
        cout << "CALCULATOR (2 values)" << endl;
        cout << "Click a botton to continue: " << endl;
        // cin >> start;
        cout << "Write: " << endl;
        cout << "- '1' for sum" << endl;
        cout << "- '2' for subtraction" << endl;
        cout << "- '3' for moltiplication" << endl;
        cout << "- '4' for power of 2" << endl;
    
        cout << "Your answer: " << endl;
        cin >> choose;
        cout << "________________________" << endl;
    
        if (choose == 1 || choose == 2 || choose == 3){
            cout << "Insert the first value: " << endl;
            cin >> first;
            cout << "Insert the second value: " << endl;
            cin >> second;
    
            if (choose == 1)
                result = first + second;
    
            if (choose == 2)
                result = first + second;
    
            if (choose == 3)
                result = first * second;
        }
    
        if (choose == 4){
            cout << "Insert the value: " << endl;
            cin >> unic;
            result = unic * unic;
        }
    
        cout << "Your result is: " << result << endl;
    }

脚注：请使用给定的代码作为参考，并尝试仔细地了解基本知识。这样做很重要。

您能帮我解决此代码中的错误吗？

1 个答案: