How to get a substring between two strings in PHP?

To get a substring between two strings there are few popular ways to do so. Below the procedures are explained with the example.
Examples:

Input:$string="hey, How are you?"
If we need to extract the substring between 
"How" and "you" then the output should be are
 
Output:"Are"

Input:Hey, Welcome to GeeksforGeeks
If we need to get the substring between Welcome and 
for then it should be to geeks as for lies within GeeksforGeeks.

Output:" to geeks"

Method 1: Firstly you have to find the ending position of the start word. Then find the starting position of the ending word after that return the substring between those indexes. 
Below program illustrate the approach:
Program:

PHP

<?php
    function string_between_two_string($str, $starting_word, $ending_word)
{
    $subtring_start = strpos($str, $starting_word);
    //Adding the starting index of the starting word to
    //its length would give its ending index
    $subtring_start += strlen($starting_word);
    //Length of our required sub string
    $size = strpos($str, $ending_word, $subtring_start) - $subtring_start;
    // Return the substring from the index substring_start of length size
    return substr($str, $subtring_start, $size);
}

$str = 'Hey, Welcome to geeksforgeeks';
$substring = string_between_two_string($str, 'Welcome', 'for');

echo $substring;

?>

Output:

 to geeks

Method 2: Using the explode() function. The explode function splits the given string on the basis of the parameter provided i.e. the separator. 
Syntax:

 $arr=explode(separator, string).

This will return an array which will contain the string split on the basis of the separator. 

• Split the list on the basis of the starting word.
• In the returned array the 2nd index will contain the words after the start word.
• In the string provided by step 2 if we again split it on the basis of the ending word then the value at first index will be the string between the starting and the ending word.

Below program illustrate the approach 
Program:

PHP

<?php
  function string_between_two_string($str, $starting_word, $ending_word){
    $arr = explode($starting_word, $str);
    if (isset($arr[1])){
        $arr = explode($ending_word, $arr[1]);
        return $arr[0];
    }
    return '';
  }

  $str = "Hey, how are you?";
  $start = "Hey";
  $end = "you";
  $substring = string_between_two_string($str, $start, $end);
  echo $substring;
?>

Output:

, how are