Simple shortcode query

*************Simple shortcode query ******************

//simple shortcode query >>>>>>>>>>>>>>

function counter_shortcode($atts, $content = null) {

    //add attribute
    extract( shortcode_atts( array(
        'title' => '',
        'icon' => ''

    ), $atts, 'counter'));

        return'

        <!--Your content here-->

        ';


}
add_shortcode('counter', 'counter_shortcode');


//For call shortcode in index.php

<?php echo do_shortcode('[counter title="Testimonail" icon="user"]');?>