Execute functions hooked on a specific action hook.

This function invokes all functions attached to action hook $tag. It is possible to create new action hooks by simply calling this function, specifying the name of the new hook using the $tag parameter.

You can pass extra arguments to the hooks, much like you can with apply_filters().

Signature

do_action( $tag, $arg = '' )
tag
 (string) The name of the action to be executed.
arg
 (mixed) Optional. Additional arguments which are passed on to the functions hooked to the action. Default empty.
Default: ''

Return

(null) Will return null if $tag does not exist in $wp_filter array.

Source

function do_action($tag, $arg = '') {
	global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter;

	if ( ! isset($wp_actions[$tag]) )
		$wp_actions[$tag] = 1;
	else
		++$wp_actions[$tag];

	// Do 'all' actions first
	if ( isset($wp_filter['all']) ) {
		$wp_current_filter[] = $tag;
		$all_args = func_get_args();
		_wp_call_all_hook($all_args);
	}

	if ( !isset($wp_filter[$tag]) ) {
		if ( isset($wp_filter['all']) )
			array_pop($wp_current_filter);
		return;
	}
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