Handle Ctrl+Z & Ctrl+C through Switch Case - C/C++
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Thread: Handle Ctrl+Z & Ctrl+C through Switch Case - C/C++

  1. #1
    Join Date
    Sep 2008
    Posts
    119

    Question Handle Ctrl+Z & Ctrl+C through Switch Case - C/C++

    Description: This code simply is a switch case that handles user inputs & checks it against the switch case. If input isn't matched each of the cases, then it goes to default. The only thing is, my switch case can not handle Ctrl+Z & Ctrl+C.

    If user inserts Ctrl+Z, my code ends up in an infinite loop even though i handle it, infinite loop looks as:

    Enter a choice: Choice is invalid.

    Enter a choice: Choice is invalid.

    Enter a choice: Choice is invalid.

    Enter a choice: Choice is invalid.

    Enter a choice: Choice is invalid.

    Enter a choice: Choice is invalid.

    Enter a choice: Choice is invalid.

    Enter a choice: Choice is invalid.

    Enter a choice: Choice is invalid.

    ==========================================

    Please look between where i put asterisks.

    Question:

    1. After user insert data, i do !cin.eof() to prevent Ctrl+Z, if user Ctrl+Z not inserted, then proceed normally & return userChoice. If Ctrl+Z is inserted, return -20(could be any number that is not among one of the cases). When -20 is returned, it will go to receiveUserInput. Thus receiveUserInput carries -20, the switch case should take -20 as a regular user input & checks it against the cases & will end up in default, and repeat the request to user without going to infinite loop! Can you tell me why i end up in infinite loop & how i can fix it?

    2. I got some issues with Ctrl+C, i got help before but it did not work. Whenever i press Ctrl+C, i get the image that you see below! I know its not easy to handle Ctrl+C. If you have some good resources to learn from, please refer me to it.

    3. Is it possible to handle Ctrl+C through try/catch/throw? Why?

    4. Right now, i'm concerned about Ctrl+Z. Ctrl+C is not a big deal for now.

    I'm looking forward to hearing from you. Any answer will be appreciated

    Code:
    #include <sstream>
    #include "MenusLayout.h"
    #include "ConsoleDesign.h"
     
    const int EXIT = -1;
    ConsoleDesign windowDes;
     
    MenusLayout::MenusLayout()
    {
            //empty constructor
    }
     
    MenusLayout::~MenusLayout()
    {
            //empty destructor
    }
     
    void MenusLayout::mainMenu()
    {
            do
            {
                    choice_is_invalid = false;
     
                    windowDes.coloringText(3);
                    cout<<"\nEnter a choice: ";
                    windowDes.coloringText(7);
     
                   //*********RETURNED***************//
                    int receiveUserInput = getUserChoice<int>();
                   //************************************//
     
                    switch(receiveUserInput)
                    {
                            case 1:
                                    //do something
                                    break;
                            case 2:
                                    //do something
                                    break;
                            case 3:
                                    //do something
                                    break;
                            case EXIT:
                                    exitApplication();
                                    break;
                            default:
                                    windowDes.coloringText(6);
                                    cout<<"Choice is invalid."<<endl;
                                    choice_is_invalid = true;
                                    break;
                    }
            }while(choice_is_invalid);
     
    }
     
    template <typename genericDataType>
    genericDataType MenusLayout::getUserChoice()
    {
            genericDataType userChoice;
            string input;
     
            getline(cin, input);
            stringstream ss(input);
     
            //**********************************//
            if(!cin.eof())
            {
                    ss >> userChoice;
                    return userChoice;
            }else{
                    return -20;
            }
           //**********************************//
    }
     
    void MenusLayout::exitApplication()
    {
            do
            {
                    choice_is_invalid = false;
     
                    windowDes.coloringText(12);
                    cout<<"\nAre you sure you want to exit - Y/N? ";
     
                    char exitConfirmation = getUserChoice<char>();
     
                    switch(exitConfirmation)
                    {
                            case 'y':
                                    exit(0);
                                    break;
                            case 'Y':
                                    exit(0);
                                    break;
                            case 'n':
                                    mainMenu();
                                    break;
                            case 'N':
                                    mainMenu();
                                    break;
                            default:
                                    windowDes.coloringText(6);
                                    cout<<"Choice is invalid - Please enter Y or N"<<endl;
                                    choice_is_invalid = true;
                                    break;
                    }
            }while(choice_is_invalid);
    }
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