<?php
class Example {
const C1 = false;
const C2 = 'I am a constant';
}
$reflection = new ReflectionClass('Example');
var_dump($reflection->getConstant('C1'));
var_dump($reflection->getConstant('C2'));
var_dump($reflection->getConstant('C3'));
?>
bool(false)
string(15) "I am a constant"
bool(false)