Load a plugin’s translated strings.

If the path is not given then it will be the root of the plugin directory.

The .mo file should be named based on the text domain with a dash, and then the locale exactly.

Signature

load_plugin_textdomain( $domain, $deprecated = false, $plugin_rel_path = false )
domain
 (string) Unique identifier for retrieving translated strings
deprecated
 (string) Use the $plugin_rel_path parameter instead.
Default: false
plugin_rel_path
 (string) Optional. Relative path to WP_PLUGIN_DIR where the .mo file resides.
Default: false

Return

(void)

Source

function load_plugin_textdomain( $domain, $deprecated = false, $plugin_rel_path = false ) {
	$locale = get_locale();
	/**
	 * Filter a plugin's locale.
	 *
	 * @since 3.0.0
	 *
	 * @param string $locale The plugin's current locale.
	 * @param string $domain Text domain. Unique identifier for retrieving translated strings.
	 */
	$locale = apply_filters( 'plugin_locale', $locale, $domain );

	if ( false !== $plugin_rel_path	) {
		$path = WP_PLUGIN_DIR . '/' . trim( $plugin_rel_path, '/' );
	} else if ( false !== $deprecated ) {
		_deprecated_argument( __FUNCTION__, '2.7' );
		$path = ABSPATH . trim( $deprecated, '/' );
	} else {
		$path = WP_PLUGIN_DIR;
	}

	// Load the textdomain according to the plugin first
	$mofile = $domain . '-' . $locale . '.mo';
	if ( $loaded = load_textdomain( $domain, $path . '/'. $mofile ) )
		return $loaded;

	// Otherwise, load from the languages directory
	$mofile = WP_LANG_DIR . '/plugins/' . $mofile;
	return load_textdomain( $domain, $mofile );
}
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