Double forward slash in regular expression

Question

I want to use preg_split to split a string on double forward slash (//) and question mark (?). I can use a single forward slash like this:

preg_split('[\/]', $string);

But

preg_split('[\//]', $string);
or
preg_split('[\/\/]', $string);

do not work.

How do you work with a double forward slash in an expression?

I would not use regex special characters like the square brackets as delimiters. It only causes confusion. If you don't want the the slash, because you need to match, then use something like `~` or `#` (a special character, you don't need in your expression) — stema, May 06 '14 at 07:50

score 5 · Accepted Answer · edited Jun 20 '20 at 09:12

5

$str= 'Hi//Hello?New World/';
$splits = preg_split( '@(\/\/|\?)@', $str );
print_r($splits);

OUTPUT :

Array
(
    [0] => Hi
    [1] => Hello
    [2] => New World/
)

enter image description here

edited Jun 20 '20 at 09:12

Community

answered May 06 '14 at 07:19

score 2 · Answer 2 · answered May 06 '14 at 07:15

/ and ? are reserved for the regex and you need to escape them when you use them literally.

$str = 'test1 // test2 // test3 ';

$array = preg_split("/\/\//", $str);
print_r($array);

For ? you can use as

$str = 'test1 ? test2 ? test3 ';

$array = preg_split("/\?/", $str);
print_r($array);

score 2 · Answer 3 · answered May 06 '14 at 07:17

You can use a different delimiter for your regex.

<?php

$str = 'hello // world // goodbye ? foo ? bar';

$array = preg_split("!//!", $str);
print_r($array);
?>

For the question mark, you can use a character class to encapsulate it. You can do one OR the other using | to separate.

$array = preg_split("!//|[?]!", $str);

3 Answers3