Can I Access Class Constant Values Dynamically Using a Variable?

Getting Class Constant Values Dynamically

Question:

Is it possible to access the value of a class constant dynamically using a variable that contains the constant's name?

Answer:

Yes, there are two methods to achieve this: using the constant function or reflection.

Method 1: Constant Function

The constant function can be used to retrieve the value of both user-defined constants declared with define and class constants:

<code class="php">class A
{
    const MY_CONST = 'myval';

    static function test()
    {
        $c = 'MY_CONST';
        return constant('self::'. $c);
    }
}

echo A::test(); // outputs "myval"</code>

Method 2: Reflection Class

A more comprehensive approach is to use reflection:

<code class="php">$ref = new ReflectionClass('A');
$constName = 'MY_CONST';
echo $ref->getConstant($constName); // outputs "myval"</code>

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