what is the use of strpos() function in php code example

Example 1: php check if string contains word

$myString = 'Hello Bob how are you?';
if (strpos($myString, 'Bob') !== false) {
    echo "My string contains Bob";
}

Example 2: strpos php

<?php
function g($string,$start,$end){
     preg_match_all('/' . preg_quote($start, '/') . '(.*?)'. preg_quote($end, '/').'/i', $string, $m);
     $out = array();

     foreach($m[1] as $key => $value){
       $type = explode('::',$value);
       if(sizeof($type)>1){
          if(!is_array($out[$type[0]]))
             $out[$type[0]] = array();
          $out[$type[0]][] = $type[1];
       } else {
          $out[] = $value;
       }
     }
  return $out;
}
print_r(g('Sample text, [/text to extract/] Rest of sample text [/WEB::http://google.com/] bla bla bla. ','[/','/]'));
?>

results:
Array
(
    [0] => text to extract
    [WEB] => Array
        (
            [0] => http://google.com
        )

)

Can be helpfull to custom parsing :)