PHP Paragraph Regular Expression

9th June 2010 - 3 minutes read time

I quite often find the need to extract a section of text from the beginning of a blog post or similar to be used as the excerpt. I normally use a function that will count the number of whole words available and return the string containing those words.

A good alternative to this, although only applicable if the original post is in HTML, is to use a regular expression to extract the contents. The following code will take a string and extract just the first paragraph of text.

$intro = '';
preg_match("/<p.*?>(.*?)<\/p>/is", $string, $matches);
if (isset($matches[1])) {
    $intro = trim(strip_tags($matches[1]));
}

If the regular expression finds any matches to paragraph tags then it strips out the HTML and trims the string so that the final output doesn't have any formatting or whitespace. The i modifier is used to make the matching case insensitive and the s modifier is used to make the "." match all characters, including new lines. Without the s modifier the result wouldn't return anything if the paragraph text contains a newline character.

This sort of excerpt extraction can be used in systems that store posts as HTML like Wordpress or Drupal.

PHP

Comments

Hi, I'm in a trouble with php paragraph replace. I've following para

{tab=Sed facilisis consequat libero}Fusce eu ligula purus, eu ultricies nisl. Fusce eu ligula purus, eu ultricies nisl. Curabitur sed leo felis. {/tab}

{tab=Curabitur ultricies sapien}Sed facilisis consequat libero, at tincidunt neque tristique vitae. {/tab}

my aim is to replace {tab=name}something{/tab} to <div class="tab">something</div>

Reg exp. i'm using is: /({tab.+?})(.*\S)({\/tab})/s

Its working fine with single line or para. but not with multiline. Can anybody suggest how to fix it. Thanks in Advance...

Submitted by webveins.in on Thu, 10/06/2011 - 10:18

Permalink
I was searching for php tutorial came across your website thanks for valuable info

Submitted by hannah on Sun, 11/19/2017 - 12:13

Permalink
valuable info thanks for sharing

Submitted by hannah on Sun, 11/19/2017 - 12:15

Permalink
valuable info thanks for sharing

Submitted by hannah on Sun, 11/19/2017 - 12:19

Permalink
I found it usefull with preg_match_all() to extract all texts paragraphs to array (RegExp: "/

(.*?)\/p>|^

(.*?)\/p>$/is"). This way I can display any paragraph I want and I know how many are in text. Thanks ;)

Submitted by TomZdulski on Thu, 12/28/2017 - 09:33

Permalink
I simply wanted to write down a quick word to say thanks to you for those wonderful tips and hints you are showing on this site.

Submitted by careen joseph on Mon, 03/12/2018 - 09:04

Permalink

Add new comment

The content of this field is kept private and will not be shown publicly.
CAPTCHA
2 + 16 =
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

Related Content

Generating Colour Palettes From Images In PHP

4th August 2024

A common web design pattern is to incorporate an image into the design of the page. This creates a tighter integration with the image and the rest of the page.

The main issue in designing a page around the image is that the colours of the page must match the image. Otherwise this creates a dissonance between the image and the styles of the site.

Read more

Validating XML Files With XML Schema Definitions In PHP

21st July 2024

XML is a useful format for configuration, data storage, and transmitting data from one system to another. As a human readable format that can be easily read by machines it quickly gained favor in lots of different systems as a mechanism for data storage.

Read more

Approximating Pi Using A Circle And A Square

26th May 2024

Pi day was a few weeks ago, but I came across this simple approximation of pi recently and decided to put together an example in PHP since it seemed pretty simple.

This approximation of pi centers around a real world example, but we can simulate this using some code.

Read more

Drawing A Parabolic Curve With Straight Lines In PHP

12th May 2024

A parabolic curve is a type of curve where every point is an equal distance from a focal point. There a number of different way to generate this sort of curve using math, but one of the simplest is to use straight lines to create the illusion of the curve.

Read more

Recreating Spotify Wrapped In PHP

17th March 2024

I quite like the end of the year report from Spotify that they call "Wrapped". This is a little application in which they tell you what your favorite artist was and what sort of genres you listened to the most during the year.

Read more