Automatic Escaping of Special Regex Characters in PHP

preg_quote

Задание 1

Given a string:

php<?php
  $str = 'file.*.txt';
?>

Escape the special regular expression characters in the string.

Задание 2

Given a string:

php<?php
  $str = 'price+[10-20]';
?>

Escape the special regular expression characters in the string.

Задание 3

Given a string:

php<?php
  $str = 'user\name@domain.com';
?>

Escape the special regular expression characters in the string.