function module_exists

7.x module.inc	`module_exists($module)`
6.x module.inc	`module_exists($module)`

Determines whether a given module exists.

$module: The name of the module (without the .module extension).

TRUE if the module is both installed and enabled.

42 calls to module_exists()

aggregator_sanitize_configuration in drupal-7.x/modules/aggregator/aggregator.module: Checks and sanitizes the aggregator configuration.
aggregator_save_category in drupal-7.x/modules/aggregator/aggregator.module: Adds/edits/deletes aggregator categories.
aggregator_save_feed in drupal-7.x/modules/aggregator/aggregator.module: Add/edit/delete an aggregator feed.
bartik_process_html in drupal-7.x/themes/bartik/template.php: Override or insert variables into the page template for HTML output.
bartik_process_page in drupal-7.x/themes/bartik/template.php: Override or insert variables into the page template.

drupal-7.x/includes/module.inc, line 274: API for loading and interacting with Drupal modules.

function module_exists($module) {
  $list = module_list();
  return isset($list[$module]);
}