How to split a string on comma that is NOT followed by a space?

Question

I want the results to be:

Cats, Felines & Cougars    
Dogs    
Snakes

This is the closest I can get.

$string = "Cats, Felines & Cougars,Dogs,Snakes";
$result = split(',[^ ]', $string);
print_r($result);

Which results in

Array
(
    [0] => Cats, Felines & Cougars
    [1] => ogs
    [2] => nakes
)

Use `\s` to match white spaces – elgis Jun 18 '14 at 19:26 — elgis, Jun 18 '14 at 19:26

score 6 · Answer 1 · answered Jun 18 '14 at 19:26

6

You can use a negative lookahead to achieve this:

,(?!\s)

In simple English, the above regex says match all commas only if it is not followed by a space (\s).

In PHP, you can use it with preg_split(), like so:

$string = "Cats, Felines & Cougars,Dogs,Snakes";
$result = preg_split('/,(?!\s)/', $string);
print_r($result);

Output:

Array
(
    [0] => Cats, Felines & Cougars
    [1] => Dogs
    [2] => Snakes
)

answered Jun 18 '14 at 19:26

Amal Murali

@JayDansand: It would actually [result in](https://eval.in/164498) `Test, Example`. – Amal Murali Jun 18 '14 at 19:31
Argh, you're right, that's what I get for skimming. Withdrawn! – Jay Dansand Jun 18 '14 at 20:29
@JayDansand: Although I'm not sure if that's what the OP expects as the output. I guess I'll just leave the answer as it is. Thanks, by the way :) – Amal Murali Jun 18 '14 at 20:33

score 5 · Accepted Answer · answered Jun 18 '14 at 19:39

the split() function has been deprecated so I'm using preg_split instead.

Here's what you want:

$string = "Cats, Felines & Cougars,Dogs,Snakes";
$result = preg_split('/,(?! )/', $string);
print_r($result);

This uses ?! to signify that we want split on a comma only when not followed by the grouped sequence.

I linked the Perl documentation on the operator since preg_split uses Perl regular expressions:

Thanks, I think this is the cleanest syntax – Jeremy Gehrs Jun 19 '14 at 00:13 — Jeremy Gehrs, Jun 19 '14 at 00:13

score 0 · Answer 3 · answered Jun 18 '14 at 19:29

If you want to split by a char, but want to ignore that char in case it is escaped, use a lookbehind assertion.

In this example a string will be split by ":" but "\:" will be ignored:

<?php
$string='a:b:c\:d';
$array=preg_split('#(?<!\\\)\:#',$string);
print_r($array);
?>

Results into:

Array ( [0] => a [1] => b [2] => c\:d )

3 Answers3