PHP Regular Expression to break apart a Serialized String

Question

I have a string of the format:

$15?1?2/:1$16E/:2$17?6?7/:6$19E/:7$3E/

I want to use preg_split() to break this down into an array but I can't seem to get the regex right. Specifically I want to get an array with all the numerical values directly following each $.

So in this case:

[0] => 15
[1] => 16
[2] => 17
[3] => 19
[4] => 3

If someone could explain the regex to me that would produce this that would be amazing.

What regex did you try? Why you couldn't get the results be more specific on your question. — Mansueli, Jul 02 '14 at 22:23

score 1 · Accepted Answer · answered Jul 02 '14 at 22:02

1

Split vs. Match All

Splitting and matching are two sides of the same coin. You don't even need to split: this returns the exact array you are looking for (see PHP demo).

$regex = '~\$\K\d+~';
$count = preg_match_all($regex, $yourstring, $matches);
print_r($matches[0]);

Output

Array
(
    [0] => 15
    [1] => 16
    [2] => 17
    [3] => 19
    [4] => 3
)

Explanation

\$ matches a $
The \K tells the engine to drop what was matched so far from the final match it returns
\d+ matches your digits

Hang tight for explanation. :)

answered Jul 02 '14 at 22:02

zx81

41,100
9
89
105

Do you have an [advice on this one](http://stackoverflow.com/questions/24541489/crontab-intervals-preg-match) too, maybe? – Daniel W. Jul 02 '14 at 22:08
@DanFromGermany Would love to help on your question, but not fully understanding the format. One example is not enough. @ me on your question if you add sample input. – zx81 Jul 02 '14 at 22:37
Worked perfectly, easy to change to fit a variety of different strings now that *I think* I understand the format. Thank you so much zx81 – ajax1515 Jul 03 '14 at 15:37

score 0 · Answer 2 · answered Jul 02 '14 at 22:04

0

Or this:

$preg = preg_match_all("/\$(\d+)/", $input, $output);
print_r($output[1]);

http://www.phpliveregex.com/p/5Rc

answered Jul 02 '14 at 22:04

Daniel W.

31,164
13
93
151

score 0 · Answer 3 · edited May 23 '17 at 12:20

Here is non-regular expression example:

$string = '$15?1?2/:1$16E/:2$17?6?7/:6$19E/:7$3E/';

$array = array_map( function( $item ) {
    return intval( $item );
}, array_filter( explode( '$', $string ) ) );

Idea is to explode the string by $ character, and to map that array and use the intval() to get the integer value.

Here is preg_split() example that captures the delimiter:

$string = '$15?1?2/:1$16E/:2$17?6?7/:6$19E/:7$3';

$array = preg_split( '/(?<=\$)(\d+)(?=\D|$)/', $string, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE );
/*
  (?<=\$)                  look behind to see if there is: '$'
  (                        group and capture to \1:
    \d+                      digits (0-9) (1 or more times (greedy))
  )                        end of \1
  (?=\D|$)                 look ahead to see if there is: non-digit (all but 0-9) OR the end of the string
*/

With a help of this post, a interesting way to get every second value from resulting array.

$array = array_intersect_key( $array, array_flip( range( 1, count( $array ), 2 ) ) );

PHP Regular Expression to break apart a Serialized String

3 Answers3