PHP reference

strstr

Returns the part of a string starting at the first occurrence of a substring.

Syntax

strstr(string $haystack, string $needle, bool $before_needle = false): string|false

Parameter	Type	Description
$haystack	string	The string to search in.
$needle	string	What to look for.
$before_needle	bool	Optional. `true` returns the part before the occurrence.

string|falsePart of the string, or `false` if the substring is not found.

The domain and the name from an email address:

<?php
 
$email = 'anna@example.com';
 
echo strstr($email, '@'), "\n";
echo strstr($email, '@', true);

Output:

@example.com
anna

To merely check that a substring is present use str_contains() — it is faster and returns a bool.

Strings — Working with strings in PHP — quotes, concatenation, length, searching, replacing and multibyte functions.