how to get substring after a string inside php code example

Example 1: get the string after a character in php

$data = "123_String";    
$whatIWant = substr($data, strpos($data, "_") + 1);    
echo $whatIWant;

Example 2: get substring after character php

<?php
$my_url = 'http://www.example.com/5478631';
echo substr($my_url, strrpos($my_url, '/' )+1)."\n";
?>
  // print: 5478631