PHP | preg_match() Function

int preg_match( $pattern, $input, $matches, $flags, $offset )

• pattern: This parameter holds the pattern to search for, as a string.
• input: This parameter holds the input string.
• matches: If matches exists then it contains results of search. The $matches[0] will contain the text that matched full pattern, $matches[1] will contain the text that matched the first captured parenthesized subpattern, and so on.
• flags: The flags can be following flags:
  • PREG_OFFSET_CAPTURE: If this flag is passed, for every match the append string offset will be returned.
  • PREG_UNMATCHED_AS_NULL: If this flag is passed, subpatterns which are not matched reports as NULL; otherwise they reports as empty string.
• offset: Usually, search starts from the beginning of input string. This optional parameter offset is used to specify the place from where to start the search (in bytes).

<?php

// Declare a variable and initialize it
$geeks = 'GeeksforGeeks';

// Use preg_match() function to check match
preg_match('/(Geeks)(for)(Geeks)/', $geeks, $matches, PREG_OFFSET_CAPTURE);

// Display matches result
print_r($matches);

?>

Array
(
    [0] => Array
        (
            [0] => GeeksforGeeks
            [1] => 0
        )

    [1] => Array
        (
            [0] => Geeks
            [1] => 0
        )

    [2] => Array
        (
            [0] => for
            [1] => 5
        )

    [3] => Array
        (
            [0] => Geeks
            [1] => 8
        )

)

<?php

// Declare a variable and initialize it
$gfg = "GFG is the best Platform.";

// case-Insensitive search for the word "GFG"
if (preg_match("/\bGFG\b/i", $gfg, $match)) 
    echo "Matched!";
else
    echo "not matched";
    
?>

Matched!