Regulární výrazy

$subject = "abcdef";
$pattern = '/def/';
preg_match($pattern, $subject, $matches);
print_r($matches); // [ "def" ]

// preg_match() podporuje i matchovaní skupin a pojmenovaných skupin
$str = "Matching (named) groups";
preg_match('/\((?P<named_match>na[^s]+d).*(g.*)/', $str, $matches);
var_dump($matches);

// array(4) {
//     [0] =>
//   string(14) "(named) groups"
//   'named_match' =>
//   string(5) "named"
//     [1] =>
//   string(5) "named"
//     [2] =>
//   string(6) "groups"
// }

$a="abc\\def\\ghi";   // abc\def\ghi
preg_match("/\\\\.*\\\\/", $a, $m);
var_dump($m);         // [ \def\ ]

$string = 'April 15, 2003';
$pattern = '/(\w+) (\d+), (\d+)/i';
$replacement = '$2th $1 / $3';
echo preg_replace($pattern, $replacement, $string);

$string = "1+2-3";
$array = preg_split('/[+-]/', $string);
print_r($array);    // [1, 2, 3]

$string = "ěščř";
$array = preg_split('//u', $string);
print_r($array);   // [ , ě, š, č, ř, ]