Printing out selected items from an enum flag

Question

I have the following enum (which later will grow larger!):

enum TrainingFilters {
    NONE    = 0,
    GAUSS   = 1,
    SOBEL   = 2,
    FEATURE = 4
};

I have to print out string representation of the all possible combination. For now, a not-leangthy switch statement works fine, but if I add more items it will be disaster!

void Manager::setFilters(int filters)
{
    QString what("Selected filters:");

    switch (filters) {
    case 0:
        what.append(" NONE ");
        break;

    case 1:
        what.append(" GAUSS ");
        break;

    case 1 | 2:
        what.append(" GAUSS SOBEL ");
        break;

    case 2:
        what.append(" SOBEL ");
        break;
    case 2 | 4:
        what.append(" SOBEL FEATURE ");
        break;

    case 4:
        what.append(" FEATURE ");
        break;

    case 1 | 4:
        what.append(" GAUSS FEATURE ");
        break;

    case 1 | 2 | 4:
        what.append(" GAUSS SOBEL FEATURE ");
        break;

    default:
        qDebug() << "Invalid FILTERS enum received!";
        return;
    }

    qDebug() << what;
    mFilters = static_cast<TrainingFilters>(filters);
}

P.S: I have a few checkbox items in the user interface, and I should do some stuff according to the checked checkboxes. I use it like this:

var a, b,c;
cbGauss.checked ? a = 1 : a = 0;
cbSobel.checked ? b = 2 : b = 0;
cbFeat.checked ? c = 4 : c = 0;

cpManager.setFilters(a | b | c);

So my qustion is what is the best/easiest/smartest way to achieve this?

Possible duplicate of [C++: Print out enum value as text](http://stackoverflow.com/questions/3342726/c-print-out-enum-value-as-text) — rbialon, Dec 31 '15 at 19:06

score 1 · Accepted Answer · answered Dec 31 '15 at 18:58

You could simply do

if (filters & 1)
    what.append("GAUSS ");
if (filters & 2)
    what.append("SOBEL ");
if (filters & 4)
    what.append("FILTER ");

And so on. This way you can easily add new ones. Of course you have to check for zero and then add NONE.

Printing out selected items from an enum flag

1 Answers1