Removing various sorts of whitespace in PHP

Question

I am looking to remove multiple line breaks using regular expression. Say I have this text:

"On the Insert tab\n \n\nthe galleries include \n\n items that are designed"

then I want to replace it with

"On the Insert tab\nthe galleries include\nitems that are designed"

So my requirement is:

it will remove all multiple newlines and will replace with one newline
It will remove all multiple spaces and will replace with one space
Spaces will be trimmed as well

I do searched a lot but couldn't find solution - the closest I got was this one Removing redundant line breaks with regular expressions.

here's for your space part:: http://stackoverflow.com/questions/2368539/php-replacing-multiple-spaces-with-a-single-space — Sudhir Bastakoti, Sep 07 '12 at 10:12
@Sudhir I can remove multiple spaces but I need remove multiple newlines also. — ARIF MAHMUD RANA, Sep 07 '12 at 10:16
See here:: http://stackoverflow.com/questions/6360566/replace-multiple-newline-tab-space — Sudhir Bastakoti, Sep 07 '12 at 10:17
@ARIFMAHMUDRANA Here is a rundown of the technique: 1) Trim the string. 2) Find all blocks of more than one white space character. 3) Iterate over them, if the block contains an `\n` character replace it with a single `\n`, if not replace it with a single space. The easiest way to do this is with `preg_replace_callback()`. I'll even give you the regex you need for free: `/\s+/`. Try and implement it yourself and if you can't get it right show what you come up with, then we can help you see what went wrong. — DaveRandom, Sep 07 '12 at 10:19
@DaveRandom the text I am working on is article so can you tell me what will happen if the I have thousands of articles and millions of spaces in that articles — ARIF MAHMUD RANA, Sep 07 '12 at 10:23
@ARIFMAHMUDRANA Well the quantity of articles is irrelevant, because no matter how you do it, you process them 1 at a time, so you only ever need to load 1 into PCRE at once. Your second point about `millions of spaces` is a good one though, and you have made me realise that `/\s{2,}/` would be a better regex for this purpose. — DaveRandom, Sep 07 '12 at 10:27

score 1 · Answer 1 · answered Sep 07 '12 at 10:11

1

Use this :

echo trim(preg_replace('#(\s)+#',"$1",$string));

answered Sep 07 '12 at 10:11

Oussama Jilal

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This will replace `\n\n` with `` when it should be replaced with `\n`. – DaveRandom Sep 07 '12 at 10:31
@Yazmat The key to this is to examine each token you detect in the string and see if it contains a new line, return a single new line if it does and return a space if it doesn't. I'll also give you a hint as to how you can easily do that on the fly: `preg_replace_callback()`. Also note that while your expression is sound and will work, it will be quite inefficient because you will be examining every block of whitespace (including a single character) where you only need to examine blocks of two or more whitespace characters. – DaveRandom Sep 07 '12 at 10:43

score 0 · Answer 2 · answered Sep 07 '12 at 10:27

0

$text = str_replace("\r\n", "\n", $text); // converts Windows new lines to Linux ones
while (strpos($text, "\n\n") != false)
    {
        $text = str_replace("\n\n", "\n", $text);
    }

That will sort out newline characters.

answered Sep 07 '12 at 10:27

Eligos

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score 0 · Accepted Answer · edited May 23 '17 at 12:18

0

$text = trim($text);
preg_replace('/\s+/', ' ', $text);
preg_replace('/(?:\s*(?:\r\n|\r|\n)\s*){2}/s', "\n", $text);

Thanks to Removing redundant line breaks with regular expressions

edited May 23 '17 at 12:18

Community

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answered Sep 08 '12 at 05:08

ARIF MAHMUD RANA

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Removing various sorts of whitespace in PHP

3 Answers3