PHP reference

mb_strpos

Finds the position of the first occurrence of a substring.

Available since: PHP 4

Syntax

mb_strpos(string $haystack, string $needle, int $offset = 0, ?string $encoding = null): int|false

Parameter	Type	Description
$haystack	string	The string to search in.
$needle	string	The substring to find.
$offset	int	The position to start searching from.
$encoding	?string	The encoding. Defaults to the internal one, usually UTF-8.

int|falseThe position of the match, counting from zero, or `false` if the substring is not found.

Position of a match:

<?php
 
var_dump(mb_strpos('Привет, мир', 'мир'));

Output:

int(8)

When there is no match, false is returned:

<?php
 
var_dump(mb_strpos('Привет, мир', 'PHP'));

Output:

bool(false)

Position 0 also looks like false in a loose comparison, so compare strictly:

<?php
 
$position = mb_strpos('PHP', 'P');
 
var_dump($position === false);
var_dump($position == false);

Output:

bool(false)
bool(true)

Always compare the result to false with ===. If you only need to know whether the substring is present, str_contains() is simpler.

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