How do do_action and add_action work?

Question

I am trying to find what exactly do_action and add_action works. I already examine with add_action but for do_action i am trying as new now. This what i tried.

Answer 1

The reason it didn't print 100, because $regularprice within anothertest() function is local to that function. The variable $regularprice used in parent mainplugin_test() function is not same as the variable used in anothertest() function, they are in separate scope.

So you need to either define the $regularprice in a global scope (which is not a good idea) or you can pass argument as a parameter to do_action_ref_array. The do_action_ref_array is the same as do_action instead it accepts second parameter as array of parameters.

Passing as argument:

function mainplugin_test() {

    $regularprice = 50;
    
    // passing as argument as reference
    do_action_ref_array('testinghook', array(&$regularprice));

    echo $regularprice; //It should print 100

}

// passing variable by reference
function anothertest(&$regularprice) {
    if(class_exists('rs_dynamic')) {
        $regularprice = 100;
    }
}
// remain same
add_action('testinghook','anothertest');