Using Regex to add whitespace

Question

I have a string like this:

text..moretext,moartxt..,asd,,gerr..,gf,erg;ds

Which is basically, variable amounts of text, followed by variable amounts of punctuation, followed by further variable amounts of text and so forth.

How can I convert the above string to this in PHP using Regex?

text. .moretext, moartxt. . ,asd, ,gerr. . ,gf, erg; ds

Each word may only have 1 character of punctuation on either side of it.

Is there a rule for when you put white space between the last of a string of consecutive punctuation and the following letter? In your example sometimes you put a space (e.g., moretext, moartxt) and sometimes you don't (e.g., . ,asd,). If you're consistent, or it doesn't matter, then the answer is very easy. — lurker
– lurker, Commented May 25, 2013 at 17:35
Priority is given to the earliest word, but if that word already has a letter on the end of it, give it to the next word. I hope this is clear, but it shouldn't matter too much. — CHRIS
– CHRIS, Commented May 25, 2013 at 17:41

Ro Yo Mi · Accepted Answer · 2013-05-25 19:27:10Z

2

Description

I would do this in two passes, first the punctuation after each word. Then a pass for the punctuation before the word.

PHP Code Example:

<?php
$sourcestring="text..moretext,moartxt..,asd,,gerr..,gf,erg;ds";
echo preg_replace('/(\w[.,;])([^\s])/i','\1 \2',$sourcestring);
?>

$sourcestring after replacement:
text. .moretext, moartxt. .,asd, ,gerr. .,gf, erg; ds


<?php
$sourcestring="text. .moretext, moartxt. .,asd, ,gerr. .,gf, erg; ds";
echo preg_replace('/([^\s])([.,;]\w)/i','\1 \2',$sourcestring);
?>

$sourcestring after replacement:
text. .moretext, moartxt. . ,asd, ,gerr. . ,gf, erg; ds

edited May 25, 2013 at 19:27

answered May 25, 2013 at 19:09

Ro Yo Mi

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Comments

HamZa · Accepted Answer · 2013-05-25 19:14:19Z

0

Let's solve this with preg_replace_callback:

Code

$string = 'text..moretext,moartxt..,asd,,gerr..,gf,erg;ds';
$chars = '\.,;'; // You need to escape some characters

$new_string = preg_replace_callback('#['.$chars.']+#i', function($m){
    return strlen($m[0]) == 1 ? $m[0].' ':implode(' ', str_split($m[0]));
}, $string); // This requires PHP 5.3+

echo $new_string; // text. .moretext, moartxt. . ,asd, ,gerr. . ,gf, erg; ds

Online demo

answered May 25, 2013 at 19:14

HamZa

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