Perl regular expression doesn't work

[a123123]

Hello. I am using code:

<?php
$patterns = array('/[^e]abcd/');
$replacements = array('abcde');
$string=$_POST['link'];
echo preg_replace($patterns, $replacements, $string);
?>

I am using array because there is more patterns, but I place one as example. This code should change to 'abcde' every string 'abcd' not followed by 'e', but it doesn't. I am doing everything the same as its described in internet, why my code doesn't work then? Thanks for help

 

BTW, I think you have mistake in verify question: "John, George, Paul and..." and when I wrote "fischer" it didn't applied, so I had to refresh site.

[JAY6390]

Firstly, I have no idea what you are on about with the verification and fischer. I'm guessing the answer is Ringo (the beatles)

 

As for your regex, it is trying to match any "abcd" that has any character before it that isn't an e

So it will match

7abcd

3abcd

aabcd

The only thing it won't match is

eabcd

[a123123]

Firstly, I have no idea what you are on about with the verification and fischer. I'm guessing the answer is Ringo (the beatles)

http://en.wikipedia.org/wiki/John_Fischer_(painter)

the beatles? i heard this word, but didn't know what it means, nevermind already solved

 

As for your regex, it is trying to match any "abcd" that has any character before it that isn't an e

So it will match

7abcd

3abcd

aabcd

The only thing it won't match is

eabcd

Yes, I know this, and that what I want. But by code doesnt work - why?

[JAY6390]

It works for me just fine. If it's not working then I am guessing your $_POST['link'] input is invalid. For example, I tried the string

eabcd .abcd

which correctly changed to

eabcd abcde

[a123123]

Good for you then this title is connected with other text box, and I am sure it is correct. Where are you using this reg exp?

[JAY6390]

Just tried it in php and changed

$string=$_POST['link'];

to

$string='eabcde .abcd';

 

and it echo's out fine

I'd recommend doing a var_dump on $_POST['link'] to make sure it has what you expect it does in it

[a123123]

Just tried it in php and changed

$string=$_POST['link'];

to

$string='eabcde .abcd';

<?php
$patterns = array('/[^e]abcd/');
$replacements = array('abcde');
$string='abcd eabcd';
echo preg_replace($patterns, $replacements, $string);
?>

doesn't work...

I'd recommend doing a var_dump on $_POST['link'] to make sure it has what you expect it does in it

Where I should place var_dump then? I need to have rather $_POST function that defined string because it should be text box.

[JAY6390]

it doesn't really matter where you have it, just put

var_dump($_POST['link']);

somewhere in your code and it will show its contents

[a123123]

It shows me "null".

My question is, why negation with [^e] doesn't work?

[JAY6390]

ok, so the problem is your input, not the regex

The regex needs to match all of the pattern, not just the [^e]

since abcd isn't in the pattern, it doesn't match or replace anything

You need to sort out your input form to get this working, your php code and regex is fine

[a123123]

Thanks, seems that it works partially. But it doesnt when abcd is followed by space, why?

[JAY6390]

it should as long as there is a character before the abcd

[a123123]

everything works fine! i love u! thanks for your help!!!

 

this space is not a big problem now, but how can I solve it?

[JAY6390]

You could substitute the

[^e]

with

(?<!e)

which means if there's not an e before the regex

[a123123]

Good idea. How can I negate backslash character (\) in these new brackets?

[JAY6390]

Like this?

(?<![e\\])

[a123123]

Compilation failed: missing terminating ] for character class at offset 12

 

interesting... what can you advice for that?

[a123123]

Well, I found answer, its triple backslash. I think I mark it as solved and make another topic because my new problem is similar. Thanks.

[JAY6390]

ah, you should actually use 4 backslashes (need to escape them both)