The program ends straight away, why?

Question

This code is supposed to repeatedly check the state of the D9 slider on an Axiom keyboard and use its value to control the pitch of a frequency.

int main()
{
    int note;
    int modwheel;
    float frequency;


    while (modwheel != 0)

    {
        note = aserveGetControl(74);
        modwheel = aserveGetControl(01);

        frequency = 440 * pow(2, (note-69) /12.0);
        aserveOscillator(1,frequency,1.0,0);
        aserveSleep(100);
    }



    return 0;
}

You forgot to initialise `modwheel` before testing its value. You also forgot to enable your compiler's warnings. — Mike Seymour, Nov 21 '14 at 15:32
Also note that `01` is an octal constant - it doesn't matter in this instance, but you need to be aware of it, otherwise you'll get very confused when one day you try to use a value such as `012`. — Paul R, Nov 21 '14 at 15:40
Don't do that - C and C++ are very different languages and in general you will get very different answers for each. — Paul R, Nov 23 '14 at 11:34

score 3 · Accepted Answer · answered Nov 21 '14 at 15:33

You never initialize modwheel, so when the while loop starts, its value is "random", i.e. it can be zero, which causes the loop to end immediately.

Use a do/while loop to ensure it has at least one iteration, or use an infinite while (true) loop with an if inside to avoid actually handling 0 as valid input.

The program ends straight away, why?

1 Answers1