Actions, Filters and Hooks

Filters take content, alter it, and return that content back to the function running the filter. Conceptually they are sort-of like PHP’s string functions– preg_replace(...) or substr(...), for example.

Actions don’t alter content in that way. Actions do things like alter global settings. They don’t process content inline.

https://ottopress.com/2011/actions-and-filters-are-not-the-same-thing/

So when am using X filter – does that mean I have to write who X fuctions once again to suit my need?

Like if X is taking ‘a’ and summing that with ‘b’ to get ‘a+b’ and returning ‘c’. And if I want it to return ‘c+2’ -> then do I have to write whole function to change it or just return final result with ‘+2’ ?

An action is a defined place in the code where you can insert your own code. So if the line do_action('init') is called, then you can hook in your own code with add_action('init','my_function'); and your function will get run at that point in the code.

A filter is like an action, but you’re expected to be acting on some variable, possibly modifying it, and returning the result.

For example, say I have this code:

$value = 5;
$value = apply_filters( 'value_adjuster', $value );

That code takes whatever $value is (in this case, five), and runs it through the “value_adjuster” filter. So if I want to modify that value, I can use a filter to do it like so:

add_filter( 'value_adjuster', 'my_filter' );
function my_filter( $original_value ) {
  $new_value = $original_value + 5;
  return $new_value;
}

Now $value will be 10 after the apply_filters function runs.

That help any?

@otto, thanks man. You don’t know how much you’ve helped me with this one. Thumbs Up!

Just one last thing, So you mean to say that as in that example – I can use any filter/function instead of value_adjuster to suit my need, right!