How to extract an ID number from a string? - php

Question

How do I retrieve the middle value using regex or preg_match?
$str = 'fxs_124024574287414=base_domain=.example.com; datr=KWHazxXEIkldzBaVq_of--syv5; csrftoken=szcwad; ds_user_id=219132; mid=XN4bpAAEAAHOyBRR4V17xfbaosyN; sessionid=14811313756%12fasda%3A27; rur=VLL;'
How do I only get values ​​from ds_user_id using regex or preg_match?

Answer 1

Use preg_match to match ds_user_id=, then forget those matched characters with \K, then match one or more digits. No capture groups, no lookarounds, no parsing all the key-value pairs, no exploding.
Code: (Demo)
$str = 'fxs_124024574287414=base_domain=.example.com; datr=KWHazxXEIkldzBaVq_of--syv5; csrftoken=szcwad; ds_user_id=219132; mid=XN4bpAAEAAHOyBRR4V17xfbaosyN; sessionid=14811313756%12fasda%3A27; rur=VLL;';
echo preg_match('~ds_user_id=\K\d+~', $str, $out) ? $out[0] : 'no match';
Output:
219132

Answer 2

Ok, nothing can beat the mickmackusa \K construct.
But, for the \K impaired engines, this is the next best thing
(\d(?<=ds_user_id=\d)\d*)(?=;)
Explained
( # (1 start), Consume many ID digits
\d # First digit of ID
(?<= ds_user_id= \d ) # Look behind, assert ID key exists before digit
\d* # Optional the rest of the digits
) # (1 end)
(?= ; ) # Look ahead, assert a colon exists
This one is a verb solution (no \K), about %30 faster.
( # (1 start), Consume many ID digits
\d # First digit of ID
(?:
(?<! ds_user_id= \d ) # Look behind, if not ID,
\d* # get rest of digits
(*SKIP) # Fail, then start after this
(?!)
|
\d* # Rest of ID digits
)
) # (1 end)
(?= ; ) # Look ahead, assert a colon exists
Some benchmarks for comparison
Regex1: (\d(?:(?<!ds_user_id=\d)\d*(*SKIP)(?!)|\d*))(?=;)
Options: < none >
Completed iterations: 50 / 50 ( x 1000 )
Matches found per iteration: 1
Elapsed Time: 0.53 s, 534.47 ms, 534473 µs
Matches per sec: 93,550
Regex2: (\d(?<=ds_user_id=\d)\d*)(?=;)
Options: < none >
Completed iterations: 50 / 50 ( x 1000 )
Matches found per iteration: 1
Elapsed Time: 0.80 s, 796.97 ms, 796971 µs
Matches per sec: 62,737
Regex3: ds_user_id=\K\d+(?=;)
Options: < none >
Completed iterations: 50 / 50 ( x 1000 )
Matches found per iteration: 1
Elapsed Time: 0.21 s, 214.55 ms, 214549 µs
Matches per sec: 233,046
Regex4: ds_user_id=(\d+)(?=;)
Options: < none >
Completed iterations: 50 / 50 ( x 1000 )
Matches found per iteration: 1
Elapsed Time: 0.23 s, 231.23 ms, 231233 µs
Matches per sec: 216,232

Answer 3

If we wish to use explode:
$str = 'fxs_124024574287414=base_domain=.example.com; datr=KWHazxXEIkldzBaVq_of--syv5; csrftoken=szcwad; ds_user_id=219132; mid=XN4bpAAEAAHOyBRR4V17xfbaosyN; sessionid=14811313756%12fasda%3A27; rur=VLL;';
$arr = explode(';', $str);
foreach ($arr as $key => $value) {
if (preg_match('/ds_user_id/s', $value)) {
$ds_user_id = explode('=', $value);
echo $ds_user_id[1];
}
}
Output
219132
Here, we can also use two non-capturing groups with a capturing group:
(?:ds_user_id=)(.+?)(?:;)
where we have a left boundary:
(?:ds_user_id=)
and a right boundary:
(?:;)
and we collect our desired digits or anything else that we wish to have using:
(.+?)
If we wish to validate our ID number, we can use:
(?:ds_user_id=)([0-9]+?)(?:;)
DEMO
and our desired value can be simply called using var_dump($matches[0][1]);.
Test
$re = '/(?:ds_user_id=)(.+?)(?:;)/m';
$str = 'fxs_124024574287414=base_domain=.example.com; datr=KWHazxXEIkldzBaVq_of--syv5; csrftoken=szcwad; ds_user_id=219132; mid=XN4bpAAEAAHOyBRR4V17xfbaosyN; sessionid=14811313756%12fasda%3A27; rur=VLL;';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Output
array(1) {
[0]=>
array(2) {
[0]=>
string(18) "ds_user_id=219132;"
[1]=>
string(6) "219132"
}
}
DEMO