PHP: How to trim off everything before certain keywords in strings?

Question

I have these type of results from a loop function,

C:/wamp/www/xxx/core/page/
C:/wamp/www/xxx/local/page/

But how can I trim off anything before core or local, so I get these only,

core/page/
local/page/

I use strstr, but I think it search for a fixed keyword only, I have two, many more keywords to match,

$string = 'C:/wamp/www/xxx/local/page/';
$output = strstr($string, '(local|core)');
var_dump($output);

I tried with preg_replace,

var_dump(preg_replace('#/(core|local)/.*#si', '/', $string));

it gives me the front part - C:/wamp/www/xxx/

Alma Do · Answer 1 · 2013-09-17T12:27:17.947

2

Your code will be like:

$sData   = 'C:/wamp/www/xxx/local/page/';
$sResult = preg_replace('/^(.*?)\/(core|local)\/(.*?)$/', '$2/$3', $sData);

edited Sep 17 '13 at 12:27

answered Sep 17 '13 at 11:39

Alma Do

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Jerry · Accepted Answer · 2013-09-17T12:39:53.443

You can use preg_replace like this:

$output = preg_replace('~^.*?((?:core|local).*$)~i', "$1", $string);

or

$output = preg_replace('~^.*?(?=core|local)~i', '', $string);

If you want to match strictly up to the folder core or local, you can use this:

$output = preg_replace('~^.*?/(?=(?:core|local)/)~i', '', $string);

Viper-7 demo

To your question:

var_dump(preg_replace('#/(core|local)/.*#si', '/', $string));

This will match /(core|local)/.* and replace it by /, which is not really what you're looking for, because you actually have to match what is before this. My first regex here is an example of that: it will match everything before (?:core|local) and then capture everything which comes afterwards into a capture group, which I'm referring to when using the backreference $1.

And well, because of the votewar going here... I added the forward slashes in the match, and you will be using less memory if you don't use a capture group at all (but using a lookahead), hence how I came to the last regex.

That looks better with backreferences, thank you, I forget about them — Alma Do, Sep 17 '13 at 11:42
That's not overcomplicated. It's actually the simplest way(s) with `preg_replace`, avoiding too many captures. — Jerry, Sep 17 '13 at 12:41

score 1 · Answer 3 · answered Sep 17 '13 at 11:46

1

Use preg_match()

<?
    $dir = "C:/wamp/www/xxx/core/page/";
    preg_match("#^.*?/((?:local|core).*/)$#i",$dir,$match);
    echo $match[1];
?>

If the first bit of the string is always the same you can use
echo ltrim($dir, "C:/wamp/www/xxx/");

answered Sep 17 '13 at 11:46

Chris

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score 0 · Answer 4 · answered Sep 17 '13 at 11:39

0

$output = substr($string, strpos($string,'local/')+strpos($string,'core/'));

answered Sep 17 '13 at 11:39

Alexandr Perfilov

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Actually, not - since will do the stuff with `C:/wamp/www/xxx/score/page/` – Alma Do Sep 17 '13 at 11:46
omg `$output = substr($string, strpos($string,'/local/')+strpos($string,'/core/')+strpos($string,'/score/')+1);` – Alexandr Perfilov Sep 17 '13 at 11:47
This will fail if `$string = 'C:/wamplocal/www/xxx/local/page/';`. You should find position of `/local/` and not only `local/`. – Glavić Sep 17 '13 at 12:06
@Jerry damn :p I knew I've missed something, but this is so stupid from my side :p Thanks a lot – Alma Do Sep 17 '13 at 12:27

score 0 · Answer 5 · answered Sep 17 '13 at 11:51

0

You can do it in a different way using str_replace. Check below.

$string = 'C:/wamp/www/xxx/local/page/';
$output = str_replace('C:/wamp/www/xxx/' , '' , $string);
var_dump($output);

It will simply trim off the left side string.

answered Sep 17 '13 at 11:51

Santosh Pradhan

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I'm sure the `www` and `xxx` are meant to be example strings and could be _any_ character... so `str_replace` won't work here. – Jerry Sep 17 '13 at 12:15

score -5 · Answer 6 · answered Sep 17 '13 at 12:01

-5

preg_replace('/.*(core|local)/', "$1", $string);

answered Sep 17 '13 at 12:01

pguardiario

53,827
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Depends on how you look at it. Add the `/` if you think it's necessary, but don't waste my time with trivialites. – pguardiario Sep 17 '13 at 12:06
That regex will fail with `C:/wamp/www/xxx/local/page/local/file` as well. Not common, but not impossible either. – Jerry Sep 17 '13 at 12:09

PHP: How to trim off everything before certain keywords in strings?

6 Answers6