//Wordpress shortcode
function rusho_alert_shortcode($atts, $content = null){
    extract(shortcode_atts(array(
      'city' => ''
    ),$atts));
    if($city == 'Dhaka'){
        $message = ''.esc_html($city).' is the most populated city';
    }elseif ($city == 'Sylhet'){
        $message = ''.esc_html($city).' is the most beautiful city';
    }elseif ($city == 'Barishal'){
        $message = ''.esc_html($city).' is the city of river';
    }else {
        $message = 'You didn\'t mention the city';
    }
    return $message;
}
add_shortcode('alert','rusho_alert_shortcode');