basic-shortcodes.php

<?php
/*
Plugin Name: JH Industry Toolkit
Plugin URI: http://github.com/jahid284
Description: Js Indusrty toolkit 
Version: 1.0.0
Author: Jahid Hasan
Author URI: http://github.com/jahid284
License: GPLv2 or later
Text Domain: jh-industry
*/

function add_google_map($atts, $content = null){
  $a = shortcode_atts( array(
        'width' => 600,
        'height' => 400,
    ), $atts );
  $map = '<iframe src="https://www.google.com/maps/embed?pb=!1m18!1m12!1m3!1d3652.3440942360044!2d90.40837231460704!3d23.735105984596913!2m3!1f0!2f0!3f0!3m2!1i1024!2i768!4f13.1!3m3!1m2!1s0x3755b8f5b23ba717%3A0x70856249be26cb13!2z4Ka54KeL4Kaf4KeH4KayIOCnreCnpw!5e0!3m2!1sbn!2sbd!4v1502351908867" width="'.$a['width'].'" height="'.$a['height'].'" frameborder="0" style="border:0" allowfullscreen></iframe>';

  return $map;
}
add_shortcode( 'gmap', 'add_google_map' );