php preg_match examples

<?php
$subject = "abcdef ghij";
echo 'String: '.$subject.'<br><br>';

$key = 'def';
$non_match = '';
if(preg_match("/^(.*)$key(.*)$/",$subject,$m)) {
        $non_match= $m[1].$m[2];
}

echo 'Text not matching {def}: '.$non_match.'<br>';

$subject = explode( " ", $subject );
foreach( $subject as $k => $v ) if( preg_match( "/abcdef/", $v )) {
  unset( $subject[$k] );
}
$subject = implode( " ", $subject );

echo 'Text not matching {abcdef}: '.$subject.'<br><br>';

$text = 'POLYGON((0 0,20 0,20 20,0 20,0 0))';
echo 'String: '.$text.'<br><br>';

preg_match('#\((.*?)\)#', $text, $match);
print 'Text in parenthesis: '.substr($match[1],1);
?>

Output:

String: abcdef ghij

Text not matching {def}: abc ghij
Text not matching {abcdef}: ghij

String: POLYGON((0 0,20 0,20 20,0 20,0 0))

Text in parenthesis: 0 0,20 0,20 20,0 20,0 0