无法重新访问内部菜单（while 循环和切换）

Question

I have the following reproducible example:

#include <string>
#include <iostream>
using namespace std;

int main()
{
    int choice;
    bool run = true;
    char inner_choice;
    bool inner_run = true;
    
    while(run != false)
    {
        cout << "Pick a selection" << endl;
        cout << "1) Case 1" << endl;
        cout << "2) Case 2" << endl;
        cout << "3) Case 3" << endl;
        cout << "4) Quit" << endl;
        cout << "Enter your choice: ";
        cin >> choice;
        
        switch(choice)
        {
            case 1: cout << "Inside case 1" << endl;
                    break;
            case 2: cout << "Inside case 2" << endl;
                    break;
            case 3: cout << "Select inner menu" << endl;
                    cout << "a) Inner case a" << endl;
                    cout << "b) Inner case b" << endl;
                    
                    while(inner_run != false)
                    {
                        cout << "q) q to go back main menu" << endl;
                        cin >> inner_choice;
                        
                        switch(inner_choice)
                        {
                            case 'a': cout << "Inside inner case a" << endl;
                                        break;
                            case 'b': cout << "Inside inner case b" << endl;
                                        break;
                            case 'q': cout << "Going back" << endl;
                                        inner_run = false;
                                        break;
                                        cin.clear();
                        }
                    }
                    break;
            case 4: cout << "Terminate" << endl;
                    run = false;
                    break;
        }
    }
    
    return 0;
}

The problem is when I select 3 for the first time, it will display the option to allow me to select the inner menu. When I select q to go back to the main menu and then to access 3 again, the option to select the inner menu is gone.

I thought this could be due to the cin stream still having the input so I placed a cin.clear() but the problem persists.

Any suggestion?

Answer 1

You executed inner_run = false; when q is entered and after that inner_run is not set to true at anywhere. This will prevent it from entering choice for the inner menu.

To fix, you should set inner_run to true before the loop like:

                    inner_run = true; // add this
                    while(inner_run != false)
                    {