The preg_match Function

The preg_match function searches a string for matches with a regular expression. The first parameter accepts the regular expression pattern, the second - the string to search, the third (optional) - an array to save found matches, the fourth (optional) - flags, the fifth (optional) - the offset of the start of the search.

Syntax

preg_match(pattern, subject, [matches], [flags], [offset]);

Flags

Flag	Constant	Description
`PREG_PATTERN_ORDER`	1	Results are sorted by patterns (default)
`PREG_SET_ORDER`	2	Results are sorted by match sets
`PREG_OFFSET_CAPTURE`	256	Returns the position of the match in the string
`PREG_UNMATCHED_AS_NULL`	512	Unmatched subpatterns are returned as NULL

Example

Let's check if the string contains digits:

<?php
	$res = preg_match('/\d+/', 'abc123');
	echo $res;
?>

Code execution result:

1

Example

Let's extract all digits from the string into an array:

<?php
	preg_match('/\d+/', 'abc123', $matches);
	var_dump($matches);
?>

Code execution result:

[0 => '123']

Example

Using named groups in a regular expression:

<?php
	preg_match('/(?P<name>\w+)\s+(?P<age>\d+)/', 'John 25', $matches);
	var_dump($matches);
?>

Code execution result:

[
	0 => 'John 25',
	'name' => 'John',
	1 => 'John',
	'age' => '25',
	2 => '25'
]

Example

Using the PREG_OFFSET_CAPTURE flag to get the match position:

<?php
	preg_match('/\d+/', 'abc123', $matches, PREG_OFFSET_CAPTURE);
	var_dump($matches);
?>

Code execution result:

[
	0 => [
		0 => '123',
		1 => 3
	]
]

Example

Search with an offset specified:

<?php
	preg_match('/\d+/', '123abc456', $matches, 0, 3);
	var_dump($matches);
?>

Code execution result:

[0 => '456']

Example

Checking the validity of an email address:

<?php
	$email = 'test@example.com';
	$res = preg_match('/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/', $email);
	echo $res ? 'Valid' : 'Invalid';
?>

Code execution result:

'Valid'

The preg_match Function

Syntax

Flags

Example

Example

Example

Example

Example

Example

See Also