Capitalize the encoded part of encoded url in PHP - php

Question

I have string urls like this:
$url = 'htttp://mysite.com/sub1/sub2/%d8%f01'
I'd like to capitalize the encoded part of an url(only %** substrings) as per example it is '%d8%f01' so final url will be :
htttp://mysite.com/sub1/sub2/%D8%F01
Probably using preg_replace(), but can't make a correct regex.
Any clues? Thanks!!!

Answer 1

You could use preg_replace_callback to convert matched %** substrings to upper case:
$url = 'http://example.com/sub1/sub2/%d8%f01';
echo preg_replace_callback('/(%..)/', function ($m) { return strtoupper($m[1]); }, $url);
Output:
http://example.com/sub1/sub2/%D8%F01
Note this will also work if not all of the URL is encoded, for example:
$url = 'http://example.com/sub1/sub2/%cf%81abcd%ce%b5';
echo preg_replace_callback('/(%..)/', function ($m) { return strtoupper($m[1]); }, $url);
Output:
http://example.com/sub1/sub2/%CF%81abcd%CE%B5
Update
It is also possible to solve this with a straight preg_replace, although the patterns and replacements are quite repetitive as you have to consider all possible hex digits in each position after the %:
$url = 'http://example.com/sub1/sub2/%cf%81abcd%ce%5b';
echo preg_replace(array('/%a/', '/%b/', '/%c/', '/%d/', '/%e/', '/%f/',
'/%(.)a/', '/%(.)b/', '/%(.)c/', '/%(.)d/', '/%(.)e/', '/%(.)f/'),
array('%A', '%B', '%C', '%D', '%E', '%F',
'%$1A', '%$1B', '%$1C', '%$1D', '%$1E', '%$1F'),
$url);
Output:
http://example.com/sub1/sub2/%CF%81abcd%CE%5B
Update 2
Inspired by #Martin I did some performance testing, and the preg_replace_callback solution typically ran about 25% faster than the preg_replace (0.0156 seconds vs 0.0220 seconds for 10000 iterations).

Answer 2

I am not at all knowledgeable with PHP, but here's an example (albeit a bodged-together one which could probably be refactored) of how to do it without Regex. There's no need to use Regex with something like this.
$str = "http://example.com/sub1/sub2/%d8%f01";
$expl = explode('%', $str);
foreach ($expl as &$val) {
if(strpos($val, 'http') === false) {
$val = '%' . strtoupper($val);
};
}
print_r(join('', $expl));