Add_action function in wordpress

Question

Well, learn to create a wordpress plugin, I downloaded one and read the codes, and I saw this. I assume that "foo" is the tag into which the action will be added.

but what exactly does array () do?

add_action('foo', array('foo1', 'foo2'));

I looked at http://codex.wordpress.org/Function_Reference/add_action and there is no clear definition about this.

Answer 1

That's right, the first argument is the tag (to which you will add the action), and the second argument indicates the function to call (i.e. your callback).

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Answer 2

add_action - , hook.

function hello_header() {
 echo "I'm in the header!"; 
}

add_action('wp_head', 'hello_header');

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http://us2.php.net/manual/en/language.pseudo-types.php#language.types.callback