PHP const not working?

Question

My class looks similar to this:

class Foo {
    const UNKNOWN = 2;

    public function doStuff($var) {
        if($var==UNKNOWN) {
            echo "Unknown state";
            return;
        }
        // other stuff
    }
}

However, I'm getting this error in doStuff():

Use of undefined constant UNKNOWN - assumed 'UNKNOWN'

What am I doing wrong? Can't I define custom constants?

Answer 1

You must use self:: or the class name when accessing the constant in your class:

if($var == self::UNKNOWN) {
    echo "Unknown state";
    return;
}