Divide a String in Half Without Cutting An Element Off

Question

I'm trying to take a string and cut it off at a certain point (basically to provide a preview of the selected text) but there may be images or similar content inside (using BBCode for this) and I was wondering if there was a simple way to do this in PHP.

Example:

$content = "blah blah blah such and such [img]imagehere[/img] blah blah";
$preview=unknownfunction($content); //cuts off at approx. 40 chars
//do not want this:
$preview="blah blah blah such and such [img]image";//this is bad because half of image is gone
//want this:
$preview="blah blah blah such and such [img]imagehere[/img]"; //this is good because even though it reached 40 chars, it let it finish the image.

Is there a simple way to do this? Or at the very least, I could remove all tags from the preview element, but I'd still like this function to not cut off any words.

First remove the "bbcoded" content, then count the remaining words and split by that (MyBB forum, for example, worked like that last time I checked) — Damien Pirsy, Feb 28 '12 at 16:38
I feel like I'm answering this often. http://stackoverflow.com/a/9202571/383402 and the other answers there. — Borealid, Feb 28 '12 at 16:40
If you can get a list of BB tags you can split the string using preg_match_all and make the calculation thereafter. Otherwise you can use a regular expression using the `[``]` characters but I'm not sure how it parses the unrecognized tags. — inhan, Feb 28 '12 at 16:44

score 1 · Answer 1 · answered Feb 28 '12 at 16:43

1

check this out :

$ php -a

php > $maxLen = 5;
php > $x = 'blah blah blah such and such [img]imagehere[/img] blah blah';
php > echo substr(preg_replace("/\[\w+\].*/", "", $x), 0, $maxLen);
blah

answered Feb 28 '12 at 16:43

Gilles Quénot

173,512
41
224
223

score 1 · Accepted Answer · answered Feb 28 '12 at 16:46

1

Heres a function that uses regex

<?php 
function neat_trim($str, $n, $delim='') {
    $len = strlen($str);
    if ($len > $n) {
        preg_match('/(.{'.$n.'}.*? )\b/', $str, $matches);
        return @rtrim($matches[1]) . $delim;
    }else {
        return $str;
    }
}


$content = "blah blah blah such and such [img]imagehere[/img] blah blah";
echo neat_trim($content, 40);
//blah blah blah such and such [img]imagehere[/img] 
?>

answered Feb 28 '12 at 16:46

Lawrence Cherone

46,049
7
62
106

For some reason this showed no text whatsoever. I'm going to keep working with it, though, to see if it ends up working. – muttley91 Feb 28 '12 at 17:07

score 1 · Answer 3 · answered Feb 28 '12 at 16:49

A problem you'll have is that you need to come up with some rules. If the string is

$str = '[img]..[img] some text here... ';

Then will you ignore the image and just extract the text? If so, you may want to use some regular expressions to strip all the BB code out of a copy of the string. But then it will consider text on both sides in an instance such as

$str = 'txt txt [img]....[/img] txtxtxt ; // will become $copystr = 'txttxt  txttxttxt';

You can get a 'marker' with strpos of the first occurrence of '[', '[img]', or an array of the elements you dont want to allow. Then cycle through those, and if they're less than your desired 'preview' length, then use that position++ as your length.

<?php
function str_preview($str,$len){
   $occ = strpos('[',$str);
   $occ = ($occ > 40) ? 40 : $occ;
   return substr($str,0,++$occ);
}
?>

something like that would work if you want to go up to the first '['. If you want to ignore [B] (or others) and allow them to be applied, then you would want to write a more complex filtering pattern that allows that. Or - if you want to make sure it doesn't cut off in the middle of a word, you have to consider the strpos(' '..) using offset to change the length how you need it. There won't be a magical 1 liner to handle it.

score 0 · Answer 4 · answered Feb 28 '12 at 17:10

One solution I found was the following

<?php
    function getIntro($content)
    {
        if(strlen($content) > 350)
        {
            $rough_short_par = substr($content, 0, 350); //chop it off at 350
            $last_space_pos = strrpos($rough_short_par, " "); //search from end: http://uk.php.net/manual/en/function.strrpos.php
            $clean_short_par = substr($rough_short_par, 0, $last_space_pos);
            $clean_sentence = $clean_short_par . "...";
            return $clean_sentence; 
        }
        else
        {
            return $content;
        }
    }
?>

It works to prevent cutting off words, but it could still cut off tags. What I might do for this is prevent images from being posted in the preview text, and have a preview image displayed which I already have stored. This will prevent cutting off images.

Divide a String in Half Without Cutting An Element Off

4 Answers4