(PHP 4, PHP 5, PHP 7)
strstr — Find the first occurrence of a string
   Returns part of haystack string starting from and including the first
   occurrence of needle to the end of
   haystack.
  
Note:
This function is case-sensitive. For case-insensitive searches, use stristr().
Note:
If you only want to determine if a particular
needleoccurs withinhaystack, use the faster and less memory intensive function strpos() instead.
haystackThe input string.
needle
  If needle is not a string, it is converted
  to an integer and applied as the ordinal value of a character.
  This behavior is deprecated as of PHP 7.3.0, and relying on it is highly
  discouraged. Depending on the intended behavior, the
  needle should either be explicitly cast to string,
  or an explicit call to chr() should be performed.
 
before_needle
       If TRUE, strstr() returns
       the part of the haystack before the first
       occurrence of the needle (excluding the needle).
      
   Returns the portion of string, or FALSE if needle
   is not found.
  
| Version | Description | 
|---|---|
| 5.3.0 | Added the optional parameter before_needle. | 
Example #1 strstr() example
<?php
$email  = 'name@example.com';
$domain = strstr($email, '@');
echo $domain; // prints @example.com
$user = strstr($email, '@', true); // As of PHP 5.3.0
echo $user; // prints name
?>