<?php

$regex = '/\d/i';
$result = preg_match($regex ,  "PHP is 2the w3eb scr4ipti5ng language of choice." );

$subject = "dd133aa2";
$pattern = '/\d+/';
preg_match($pattern, $subject, $matches, PREG_OFFSET_CAPTURE);
print_r($matches);

$subject = "dd133aa2";
$pattern = '/\d+/';
preg_match_all($pattern, $subject, $matches, PREG_OFFSET_CAPTURE);
print_r($matches);

$subject = array("dd133aa2", "kk1ff3");
$pattern = '/\d+/';
$result = preg_replace($pattern, 'Z', $subject);
print_r($result);

$subject = "dd133aa2";
$pattern = '/\d+/';
$result = preg_replace_callback($pattern, function($matches) {
				//$matches [0] => 133
				//$matches [0] => 2
				return 'Z';
		  }, $subject);
//print_r($result);

$subject = array("dd133aa2", "kk1ff3", "ddsdfd");
$pattern = '/\d+/';
$result = preg_grep($pattern, $subject);
$result2 = preg_grep($pattern, $subject, PREG_GREP_INVERT);
print_r($result);
print_r($result2);

$subject = "dd133aa2cc";
$pattern = '/(\d+)/';
$result = preg_split($pattern, $subject);
$result2 = preg_split($pattern, $subject, null, PREG_SPLIT_DELIM_CAPTURE);
print_r($result);
print_r($result2);

preg_match('/(?:\D+|<\d+>)*[!?]/', 'foobar foobar foobar');
$result = preg_last_error();//PREG_BACKTRACK_LIMIT_ERROR 调用回溯限制超出
//print_r($result);

$subject = "dd.a?a2cc";
$result = preg_quote($subject);
$result2 = preg_quote($subject, 'a');
print_r($result);
//print_r($result2);