带有 switch() 的 C++ 递归函数返回错误数据

Question

我正在做一个需要显示一些菜单的项目，其中一些有子菜单。到目前为止，我已经创建了一个返回用户选择的字符的函数，问题是在菜单之间来回多次后返回值是垃圾，它与 cin 被刷新但我只是找不到必须清除的“点”... 我在不同的地方尝试了cin.clear();，结果好坏参半，我错过了什么？

输出：

#include <iostream>
#include <string>
#include <vector>
#include <exception>
#include <istream>
using namespace std;

char Menu() {
    char ch;
    //ch = NULL;
    //cin.clear();
    cout << "++++++++++++++++++++++++++++++++++++++++++++" << endl;
    cout << "+               MAIN MENU                  +" << endl;
    cout << "++++++++++++++++++++++++++++++++++++++++++++" << endl;
    cout << "| 1. Enter a new contract.                 |" << endl;
    cout << "| 2. Cancel an active conract.             |" << endl;
    cout << "| 3. Edit a cotract.                       |" << endl;
    cout << "| 0. Exit                                  |" << endl;
    cout << "++++++++++++++++++++++++++++++++++++++++++++" << endl;
    cin  >> ch; 

    switch (ch) {
        //cin.clear();
        case '1':
            return ch;
            break;
        case '2':
            return ch;
            break;
        case '3':
            //cin.clear();
             cout << "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++" << endl;
             cout << "+                -== Edit a cotract ==-                  +" << endl;
             cout << "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++" << endl;
             cout << " What would like to edit?                                |" << endl;
             cout << " a) Cover amount.                                        |" << endl;
             cout << " b) Add a family memeber.(Applyes to Health insurances)  |" << endl;
             cout << " 0. Return                                               |" << endl;
             cout << "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++" << endl; 
             cin  >> ch;
             if(ch == '0') {       
                 //cin.clear();     
                 Menu();
             } else if((ch >= 'a') && (ch <= 'b')) {
                 return ch;
             } else {
                 cout << "Wrong input ! ! !" << endl;
                 Menu();
                 return ch;
            }
            break;
        case '0':
            cout << "Exiting bye!" << endl;
            break;
        default:
            cout << "Wrong input ! ! !" << endl;
            Menu();
            break;
    }         
}

int main() {
    char choise;
    choise = Menu();
    cout << "selected: " << choise << endl;

    system("PAUSE");
    return 0;
}

Answer 1

        default:
               cout << "Wrong input ! ! !" << endl;
               Menu();
               break;

您调用了另一个Menu() 来获取输入，但没有将其返回值返回给调用者main()。

将其更改为return Menu();。