How to find and replace string between two tags using regex in PHP?

Question

If we have a text like this:

[SYS 1]Page 1 from 2:[/SYS]

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard ...

[SYS 2]Page 2 from 2:[/SYS]

It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged.

How should I keep only text between [SYS] and [/SYS] tags? like this:

Page 1 from 2:

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard ...

Page 2 from 2:

It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged.

I think the following regex would find the text inside two tags without attributes:

/\[SYS\](.+?)\[\/SYS\]/

But how should I replace the entire element with the inner text (or any other string) for that tag?

Your regex looks close (and good), but I would use this: /\[SYS \d+\](.*?)\[\/SYS\]/ ... find on this, and replace with the first capture group. — Tim Biegeleisen
– Tim Biegeleisen, Commented Aug 25, 2016 at 14:59

Jan · Accepted Answer · 2016-08-25 15:10:09Z

2

Use the following expression:

\[SYS[^]]*\](.+?)\[/SYS\]

And replace with $1, see a demo on regex101.com.

In PHP:

$regex = '~\[SYS[^]]*\](.+?)\[/SYS\]~';
$string = preg_replace($regex, '$1', $your_original_string);

See a demo for the complete code on ideone.com.

answered Aug 25, 2016 at 15:10

Jan

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Thomas Ayoub · Accepted Answer · 2016-08-25 15:01:44Z

0

You can replace like so:

$re = "/\\[\\/?SYS(?:\\s\\d+)?\\]/";
$str = "[SYS 1]Page 1 from 2:[/SYS]";
echo preg_replace($re, "", $str)

answered Aug 25, 2016 at 15:01

Thomas Ayoub

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5 Comments

asDca21 Over a year ago

It will remove "[SYS n]" and "[/SYS]" only? what if I want to replace the text between these tags later?

Thomas Ayoub Over a year ago

@asDca21 then use $re = "/\\[SYS \\d+\\](.*?)\\[\\/SYS\\]/";

Jan Over a year ago

@ThomasAyoub: You have far more backslashes then needed here :) Also, consider using another delimiter, e.g. ~.

Thomas Ayoub Over a year ago

@Jan which backslash would you remove?

Jan Over a year ago

See answer above :)

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