get_file_data()

function get_file_data( $file, $default_headers, $context = '' ) {
	// We don't need to write to the file, so just open for reading.
	$fp = fopen( $file, 'r' );

	if ( $fp ) {
		// Pull only the first 8 KB of the file in.
		$file_data = fread( $fp, 8 * KB_IN_BYTES );

		// PHP will close file handle, but we are good citizens.
		fclose( $fp );
	} else {
		$file_data = '';
	}

	// Make sure we catch CR-only line endings.
	$file_data = str_replace( "r", "n", $file_data );

	/**
	 * Filters extra file headers by context.
	 *
	 * The dynamic portion of the hook name, `$context`, refers to
	 * the context where extra headers might be loaded.
	 *
	 * @since 2.9.0
	 *
	 * @param array $extra_context_headers Empty array by default.
	 */
	$extra_headers = $context ? apply_filters( "extra_{$context}_headers", array() ) : array();
	if ( $extra_headers ) {
		$extra_headers = array_combine( $extra_headers, $extra_headers ); // Keys equal values.
		$all_headers   = array_merge( $extra_headers, (array) $default_headers );
	} else {
		$all_headers = $default_headers;
	}

	foreach ( $all_headers as $field => $regex ) {
		if ( preg_match( '/^(?:[ t]*<?php)?[ t/*#@]*' . preg_quote( $regex, '/' ) . ':(.*)$/mi', $file_data, $match ) && $match[1] ) {
			$all_headers[ $field ] = _cleanup_header_comment( $match[1] );
		} else {
			$all_headers[ $field ] = '';
		}
	}

	return $all_headers;
}

/**
 * Register stylesheet and scripts
 * Set the version of each the version of the plugin. 
 */
function register_plugin_styles_scripts() {
	// Set the file path to a variable.
	$file_path = plugin_dir_path( __DIR__ ) . 'example-plugin-file.php';
	// Read the version number from the main plugin file then set it to a variable.
	$plugin_data = get_file_data( $file_path, array(
		'Version' => 'Version'
	) );

	if ( ! empty( $plugin_data['Version'] ) ) {
		// The the value of the Version header to a variable.
		$ver = $plugin_data['Version'];

		// Use the variable, $ver, in more than one stylesheet/script to bust cache when the plugin gets updated.
		gc_enqueue_style( 'public-style', plugins_url( 'path/to/stylesheet.css' ), array(), $ver );
		gc_enqueue_script('public-script', plugins_url( 'path/to/script.js' ), array(), $ver , true);
	}
}