c++ - 为什么我的 do 循环运行了几次并且不要求输入？

Question

我使用 Visual Studio Community 2017 进行 C++ 编程。我有以下代码。在这里，do while 循环运行了几次并且不会因为询问输入它应该在哪里而停止。但是，在最后一个 switch case 程序中，如果我输入 1 而不是 n，程序运行良好。请帮忙!!!

// Welcome2018.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include<iostream>
#include<bitset>
using namespace std;

int main()
{
    string month[] = { "January", "February", "March", "April", "May", "June", "July", "August" "September", "October", "November", "December" };
    int m, d, answer;
    cout << "Welcome 2018!!!" << endl;
    do
    {
        cout << "Enter the number corresponding to the month you want displayed" << endl;
        cin >> m;
        switch (m)
        {
        case 1:
            cout << month[0] << endl;
            cout << "Enter the date to know the day it is/will be" << endl;
            cin >> d;
            if (d == 7 || d == 14 || d == 21 || d == 28)
            {
                cout << "The day on " << d << " January is Sunday!" << endl;
            }
            else if (d == 1 || d == 8 || d == 15 || d == 22 || d == 29)
            {
                cout << "The day on " << d << " January is Monday!" << endl;
            }
            else if (d == 2 || d == 9 || d == 16 || d == 23 || d == 30)
            {
                cout << "The day on " << d << " January is Tuesday!" << endl;
            }
            else if (d == 3 || d == 10 || d == 17 || d == 24 || d == 31)
            {
                cout << "The day on " << d << " January is Wednesday!" << endl;
            }
            else if (d == 4 || d == 11 || d == 18 || d == 25)
            {
                cout << "The day on " << d << " January is Thursday!" << endl;
            }
            else if (d == 5 || d == 12 || d == 19 || d == 26)
            {
                cout << "The day on " << d << " January is Friday!" << endl;
            }
            else if (d == 6 || d == 13 || d == 20 || d == 27)
            {
                cout << "The day on " << d << " January is Saturday!" << endl;
            }
        }
        cout << "Are you sure you want to quit?" << endl;
        cout << "Enter Y/N based on your choice:";
        cin >> answer;
        switch (answer)
        {
        case 1:
            answer = 1;

        case 'n':
            answer = 1;

        default:
            answer = 2;
        }
    } while (answer = 1);
    cout << "Thank You and Come Again!!!" << endl;
    return 0;
}

Answer 1

您的代码存在一些问题:

一个。在最后一个 while 语句中，您应该使用检查相等性的“==”运算符，而不是执行赋值的“=”运算符。

while (answer == 1)

在最后一个 switch case 中，你应该在每个 case 的末尾添加一个 break 命令。否则，它也会自动执行默认选项下的代码块。

    switch (answer)
    {
        case 1:
            answer = 1;
            break;

        case 'n':
            answer = 1;
            break;

        default:
            answer = 2;
            break;
    }

第一个 switch-case block 目前只包含一个 case。因此，它并不是真正需要的。