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get_available_languages() WP 3.0.0

Get all available languages based on the presence of *.mo files in a given directory.

The default directory is WP_LANG_DIR.

Hooks in function
Return

Array. An array of language codes or an empty array if no languages are present. Language codes are formed by stripping the .mo extension from the language file names.

Usage

get_available_languages( $dir );
$dir(string)
A directory to search for language files.
Default: WP_LANG_DIR

Code of get available languages: wp-includes/l10n.php WP 5.2.1

<?php
function get_available_languages( $dir = null ) {
	$languages = array();

	$lang_files = glob( ( is_null( $dir ) ? WP_LANG_DIR : $dir ) . '/*.mo' );
	if ( $lang_files ) {
		foreach ( $lang_files as $lang_file ) {
			$lang_file = basename( $lang_file, '.mo' );
			if ( 0 !== strpos( $lang_file, 'continents-cities' ) && 0 !== strpos( $lang_file, 'ms-' ) &&
				0 !== strpos( $lang_file, 'admin-' ) ) {
				$languages[] = $lang_file;
			}
		}
	}

	/**
	 * Filters the list of available language codes.
	 *
	 * @since 4.7.0
	 *
	 * @param array  $languages An array of available language codes.
	 * @param string $dir       The directory where the language files were found.
	 */
	return apply_filters( 'get_available_languages', $languages, $dir );
}