<?php

// This tests whether a pattern matches a string.
$match = preg_match('/p([a-z]+)ch/', 'peach', $matches);
echo $match ? "true\n" : "false\n";

// In PHP, we don't need to compile the regular expression separately.
// We can use it directly in the preg_* functions.

// This finds the match for the regexp.
preg_match('/p([a-z]+)ch/', 'peach punch', $matches);
echo $matches[0] . "\n";

// This also finds the first match but returns the
// start and end indexes for the match instead of the
// matching text.
preg_match('/p([a-z]+)ch/', 'peach punch', $matches, PREG_OFFSET_CAPTURE);
echo "idx: [" . $matches[0][1] . " " . ($matches[0][1] + strlen($matches[0][0])) . "]\n";

// The preg_match function includes information about
// both the whole-pattern matches and the submatches
// within those matches.
preg_match('/p([a-z]+)ch/', 'peach punch', $matches);
print_r($matches);

// To find all matches for a regexp, use preg_match_all.
preg_match_all('/p([a-z]+)ch/', 'peach punch pinch', $matches);
print_r($matches[0]);

// Providing a limit to preg_match_all will limit the number
// of matches.
preg_match_all('/p([a-z]+)ch/', 'peach punch pinch', $matches, PREG_SET_ORDER, 2);
print_r($matches);

// The preg_replace function can be used to replace
// subsets of strings with other values.
$result = preg_replace('/p([a-z]+)ch/', '<fruit>', 'a peach');
echo $result . "\n";

// The preg_replace_callback function allows you to transform matched
// text with a given function.
$result = preg_replace_callback('/p([a-z]+)ch/', function($matches) {
    return strtoupper($matches[0]);
}, 'a peach');
echo $result . "\n";