Why does switch always run default? (with break; included)

问题

C++ newbie trying to make a simple text game on a 2D array.

When I use the switch statement as shown. It will always print the default value, regardless of what else happens.

From other threads and forums I found it probably has something to do with the getch() and that it returns the char as well as \n.

I have tried for an hour now but I can not solve this. The reason I use getch() is this: C++ change canonical mode in windows (for reference).

Part of my code now:

//Set up game field
generateField();
setPlayerStart();

//printGameInfo(); TO BE MADE

//Start game while loop
int userInput;

do{
    //system("cls"); DISABLED FOR TESTING PURPOSES
    printField();
    userInput = getch();

    switch(userInput){
        case 72:{ //ARROW UP
            cout << "1What" << endl; //ALSO FOR TESTING PURPOSES
            break;
        }

        case 80:{ //ARROW DOWN
            cout << "2What" << endl;
            break;
        }

        case 75:{ //ARROW LEFT
            cout << "3What" << endl;
            break;
        }

        case 77:{ //ARROW RIGHT
            cout << "4What" << endl;
            break;
        }

        case 113:{ //"q"
            return false; //Quit game
        }

        default:{
            cout << "Default..." << endl;
        }
    }
} while(userInput != 5);

回答1:

Um, I assume you've forgotten how to receive extended keys..

It comes with 0xe0 when extended keys, and it comes with 0x00 when function key (F1-F12)

Change it

userInput = getch();

into

userInput = getch();
if (userInput == 0xe0) // for extended keys
{
    userInput = getch();
}
else if (userInput == 0x00) // for function keys
{
    userInput = getch();
}

回答2:

Since this is Windows, you can use ReadConsoleInput to read key events. I've separated the parts into functions, but I don't really think the return semantics of handleInput is all that great.

#include <iostream>
#include <stdexcept>
#include <windows.h>

HANDLE getStdinHandle() {
    HANDLE hIn;
    if ((hIn = GetStdHandle(STD_INPUT_HANDLE)) == INVALID_HANDLE_VALUE) {
        throw std::runtime_error("Failed to get standard input handle.");
    }

    return hIn;
}

WORD readVkCode(HANDLE hIn) {
    INPUT_RECORD rec;
    DWORD numRead;
    while (ReadConsoleInput(hIn, &rec, 1, &numRead) && numRead == 1) {
        if (rec.EventType == KEY_EVENT && rec.Event.KeyEvent.bKeyDown) {
            return rec.Event.KeyEvent.wVirtualKeyCode;
        }
    }

    throw std::runtime_error("Failed to read input.");
}

bool handleInput(WORD vk) {
    switch (vk) {
        case VK_UP:
            std::cout << "up\n";
            break;

        case VK_DOWN:
            std::cout << "down\n";
            break;

        case VK_LEFT:
            std::cout << "left\n";
            break;

        case VK_RIGHT:
            std::cout << "right\n";
            break;

        case 'Q': //it's Windows; ASCII is safe
            return true;
    }

    return false;
}

int main() {
    try {
        auto hIn = getStdinHandle();

        while (auto vk = readVkCode(hIn)) {
            if (handleInput(vk)) {
                return 0;
            }
        }
    } catch (const std::exception &ex) {
        std::cerr << ex.what();
        return 1;
    }
}