Remove part of a string with regex

Question

I'm trying to strip part of a string (which happens to be a url) with Regex. I'm getting better out regex but can't figure out how to tell it that content before or after the string is optional. Here is what I have

$string='http://www.example.com/username?refid=22';
$new_string= preg_replace('/[/?refid=0-9]+/', '', $string);
echo $new_string;

I'm trying to remove the ?refid=22 part to get http://www.example.com/username

Ideas?

EDIT I think I need to use Regex instead of explode becuase sometimes the url looks like http://example.com/profile.php?id=9999&refid=22 In this case I also want to remove the refid but not get id=9999

Community · Accepted Answer · 2020-06-20 09:12:55Z

9

parse_url() is good for parsing URLs :)

$string = 'http://www.example.com/username?refid=22';

$url = parse_url($string);

// Ditch the query.
unset($url['query']);

echo array_shift($url) . '://' . implode($url);

CodePad.

Output

http://www.example.com/username

If you only wanted to remove that specific GET param, do this...

parse_str($url['query'], $get);

unset($get['refid']);

$url['query'] = http_build_query($get);

CodePad.

Output

http://example.com/profile.php?id=9999

If you have the extension, you can rebuild the URL with http_build_url().

Otherwise you can make assumptions about username/password/port and build it yourself.

Update

Just for fun, here is the correction for your regular expression.

preg_replace('/\?refid=\d+\z/', '', $string);

[] is a character class. You were trying to put a specific order of characters in there.
\ is the escape character, not /.
\d is a short version of the character class [0-9].
I put the last character anchor (\z) there because it appears it will always be at the end of your string. If not, remove it.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Apr 19, 2011 at 4:24

alex

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7 Comments

alex Over a year ago

@BandonRandon My code above covers the case where you only want to remove one GET param.

Brooke. Over a year ago

@alex, is that method faster/standard over regex?

alex Over a year ago

@Bandon Regexs are usually slow. Anyway, this method should be easier to read and that's what's important.

Brooke. Over a year ago

@Alex, sorry to be a pain but it seems that URL is being encoded with %3B which is hex for ; CodePad

alex Over a year ago

@Bandon What string are you using for input?

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Galen · Accepted Answer · 2011-04-19 04:25:06Z

4

Dont use regexs if you dont have to

echo current( explode( '?', $string ) );

answered Apr 19, 2011 at 4:25

Galen

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