Add placeholder to form elements in Drupal

template.php

/**
* $vars['#id''] = Form ID, can be found via Krumo
* $vars['field_name'] = Name of the input element you want to access
*/

function theme_form_alter(&$vars) {
	//krumo($vars);

	if( $vars['#id'] = " ") {

		$vars['field_name']['#attributes']['placeholder'] = "Placeholder";
	}
}