你能帮我解决这段代码中的错误吗？

Question

我最近开始学习C++，我正在尝试创建一个带有一些操作的“计算器”。但我被困在字符串 26 (cin >> choose;) 中，这似乎没有反应。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，但它继续执行我写的所有“cout”操作，没有给我用“cin”写我的值的可能性。

Answer 1

您的代码中存在几个问题，

在 C++ 中，= 代表赋值来检查值是否相等，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)

当条件（if/else 或循环 for/while）下有不止一行代码时，您需要将它们显式地阻止在大括号内。因此，如果首先将 if 块放入 this

 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 条件也是如此。
也没有理由在开始时接受输入。
如果您修复了所有错误，您应该会得到这样的代码 ->

    //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，并尝试仔细理解基础知识。你这样做很重要。

你能帮我解决这段代码中的错误吗？

Can you help me to solve errors in this code?

c++

cout

operation

cin