scanf doesn't work in switch, which is itself in while loop

Question

scanf doesn't work in switch, which is itself in a while loop. I tried to find an answer in search already, but I didn't. So, if you know needed topic - write it please.

I'm trying to write code for a task in book, to make computer simulator "Simpletron", maybe somebody knows it.

while (memory[instructionCounter] != 4303)
{
    //счетчик проходов по циклу
    printf ("--> проход %d\n", instructionCounter);

    instructionRegister = memory[instructionCounter];
    operationCode = instructionRegister / 100;
    operand = instructionRegister % 100;

    //проверка операнда перед циклом
    printf ("--> значение операнда перед циклом: %d\n", operationCode);

    switch (operationCode)
    {
        case 10:
            printf ("\n***\t" "Введите значение переменной:\t\t" "***\n");
            scanf ("%d", &memory[operand]);
            break;

        case 20:
            printf ("%d", memory[operand]);
            break;

        case 21:
            printf ("***\t" "Симплетрон закончил вычисления.\t\t\t\t" "***\n");
            break;

        default:
            printf ("***\t" "Симплетрон закончил вычисления.\t\t\t\t" "***\n");
            break;
    }

    ++instructionCounter;
}

what do you mean about not working? the function is called and it is not saving the value? or is it no even being called? — Gabriel Mesquita, Aug 19 '17 at 13:50
Are you sure that operation code is coming with the value 10? — Gabriel Mesquita, Aug 19 '17 at 13:54
change this operationCode = instructionRegister / 100; to this operationCode = 10; the scanf is being called? — Gabriel Mesquita, Aug 19 '17 at 13:56
this value is right, it is taken from 4-digit value of instructionRegister (wich can be of different value). I mean, its the way to extract first 2 digits from instructionRegister. — Урузмаг Хадонов, Aug 19 '17 at 14:03
The problem is that the needed case in switch is selected correctly (because printf function just before scanf works correctly), but scanf is skipped — Урузмаг Хадонов, Aug 19 '17 at 14:06
Take a look at this: https://stackoverflow.com/questions/2303300/scanf-in-while-loop?rq=1 maybe you should consider not using scanf — Gabriel Mesquita, Aug 19 '17 at 14:07

scanf doesn't work in switch, which is itself in while loop

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