vb.org Archive - substr is BAD! fetch_trimmed

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- - substr is BAD! fetch_trimmed_title is GOOD! (https://vborg.vbsupport.ru/showthread.php?t=136982)

substr is BAD! fetch_trimmed_title is GOOD!

A little note for all coders.

I was inspecting MOD:
Cyb - Advanced Forum Statistics
https://vborg.vbsupport.ru/showthread.php?t=122986

And saw that php's substr(); function is used there.
For example:

PHP Code:


		
			
$getstats_starter[username] = substr($getstats_starter[username], 0, $trimusername) . '...';

substr(); is a bad one for cutting words up to set limit.

You have to use fetch_trimmed_title(); function which is built-in vbulletin.

You asked why?
1-st, VB's uses this function to cut thread titles.
2-nd, most forum uses UTF8.

For example Russian letter in UTF-8 will look like:

PHP Code:


		
			
&_236;

(you have to replace _ with #)
So when you type some word in Russian which consists of 5 letter it will look like:

PHP Code:


		
			
&_236;&_236;&_236;&_236;&_246;

(you have to replace _ with #)
And in this way it is storied in databse.
So it it 30 symbols if you count.

When you use substr(); function you cut by symbols and not by letters!

So if you set to with substr(); function to cut after 27 letter and you will cut the example above you will get:

PHP Code:


		
			
&_236;&_236;&_236;&_236;&_2

As you see the last letter in UTF-8 format was cuted.

And when this one will be displayed on the webpage you will see a bug.

That is why you have to use fetch_trimmed_title(); function.
As it cuts only whole words.
fetch_trimmed_title() relies on spaces when cutting.

If me return to
Cyb - Advanced Forum Statistics
https://vborg.vbsupport.ru/showthread.php?t=122986

in all code I replaced lines like:

PHP Code:


		
			
$getstats_starter[username] = substr($getstats_starter[username], 0, $trimusername) . '...';

with a good one:

PHP Code:


		
			
$getstats_starter[username] = fetch_trimmed_title($getstats_starter[username], $trimusername);

Here how this function looks like in:
functions.php

PHP Code:


		
			
// #############################################################################
/**
* Trims a string to the specified length while keeping whole words
*
* @param        string  String to be trimmed
* @param        integer Number of characters to aim for in the trimmed string
*
* @return       string
*/

Quote:

Originally Posted by Makc666 (Post 1163145)

For example Russian letter in UTF-8 will look like:

PHP Code:


		
			
&_236;

So when you type some word in Russian which consists of 5 letter it will look like:

PHP Code:


		
			
&_236;&_236;&_236;&_236;&_246;

Excuse me, where it look like this?
In UTF8 any character in the Unicode standard, yet the initial encoding of byte codes and character assignments for UTF-8 is backwards compatible with ASCII. So, dependency of character it may be represent from 1 (first 127 characters ASCII) to 4 bytes. Russian Cyrillic characters in UTF-8 represents by 2 byte per character.

Your example is strange, and I can't represent it on my system. I'm guess what you meant HTML mnemonic entities, but in this case mnemonic must look like

PHP Code:


		
			
&#236;

not like

PHP Code:


		
			
&_236;

Quote:

Originally Posted by Makc666 (Post 1163145)

And in this way it is storied in databse.

If my guess about html-entities is true, this behaviour you get only with mismatching used character encodings. For example, on vbulletin board you use UTF8 character encoding, but stores information in database (or tables, or may by only row) with another, single-byte charset, for example windows-1251 (CP1251, microsoft-1251). In this case, this transformation made by browser, to allow store characters, which are not be acceptable by form (if charsets correctly provided in HTML-code).

On my board on UTF-8 with database collation utf8_general_ci I'm haven't this troubles - all Russian and many more characters saved as is, without similar transformation.

Quote:

Originally Posted by Makc666 (Post 1163145)

When you use substr(); function you cut by symbols and not by letters!

So, about HTML-entities I'm wrote above. But we still has problem on not ASCII characters, which are be represent more then 1 byte per character. PHP function substr() do not handle characters (or symbols if you wish), it is truncate string by amount of bytes (keep in mind it is same in ASCII)!
So, if you wish cut by characters, you just may use multibyte functions like mb_substr() (which comes from mbstring extension) or iconv_substr() (this is from "more standard" and widely distributed iconv).

So, if none of this extension available, in multibyte strings, you may safely emulate substr by regular expression on this manner:

PHP Code:


		
			
$getstats_starter['username'] = preg_replace('#(.{0,' . (int)$trimusername . '}.*?)[^\pL].*#u', '\\1', $getstats_starter['username']);

That's all!! You don't need bulky functions!

Or, for clarity, you may wrap it in function, if wish:

PHP Code:


		
			
function pcre_trim ($title, $chars = 70){
return preg_replace('#(.{0,' . (int)$chars . '}.*?)[^\pL].*#u', '\\1', $title);
}

//Anywhere after, use it:
$getstats_starter['username'] = pcre_trim($getstats_starter['username'], $trimusername);

Quote:

Originally Posted by Hubbitus (Post 1569185)

PHP Code:


		
			
&#236;

not like

PHP Code:


		
			
&_236;

If you try to quote your post or my post here with

PHP Code:


		
			
&#236;

you will get a letter instead of code...

Try to post something like:

PHP Code:


		
			
&_236;&_236;&_236;&_236;&_236;&_236;

(you have to replace _ with #)

You will get this one:

PHP Code:


		
			
&#236;ììììì

With VBB 3.7 , Has it effect ?

This post will apply regardless of vBulletin version - it will apply as long the the substr() function behaves like it currently does.

X vBulletin 3.8.12 by vBS Debug Information
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Phrase Groups Available:

X vBulletin 3.8.12 by vBS Debug Information
Page Generation 0.01177 seconds Memory Usage 1,765KB Queries Executed 10 (?)
More Information
Template Usage: (1)ad_footer_end (1)ad_footer_start (1)ad_header_end (1)ad_header_logo (1)ad_navbar_below (18)bbcode_php_printable (4)bbcode_quote_printable (1)footer (1)gobutton (1)header (1)headinclude (6)option (1)post_thanks_navbar_search (1)printthread (5)printthreadbit (1)spacer_close (1)spacer_open Phrase Groups Available: global postbit showthread	Included Files: ./printthread.php ./global.php ./includes/init.php ./includes/class_core.php ./includes/config.php ./includes/functions.php ./includes/class_hook.php ./includes/modsystem_functions.php ./includes/class_bbcode_alt.php ./includes/class_bbcode.php ./includes/functions_bigthree.php Hooks Called: init_startup init_startup_session_setup_start init_startup_session_setup_complete cache_permissions fetch_threadinfo_query fetch_threadinfo fetch_foruminfo style_fetch cache_templates global_start parse_templates global_setup_complete printthread_start bbcode_fetch_tags bbcode_create bbcode_parse_start bbcode_parse_complete_precache bbcode_parse_complete printthread_post printthread_complete
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