Split a single string into an array using specific Regex rules - php

Question

I'm processing a single string which contains many pairs of data. Each pair is separated by a ; sign. Each pair contains a number and a string, separated by an = sign.
I thought it would be easy to process, but i've found that the string half of the pair can contain the = and ; sign, making simple splitting unreliable.
Here is an example of a problematic string:
123=one; two;45=three=four;6=five;
For this to be processed correctly I need to split it up into an array that looks like this:
'123', 'one; two'
'45', 'three=four'
'6', 'five'
I'm at a bit of dead end so any help is appreciated.
UPDATE:
Thanks to everyone for the help, this is where I am so far:
$input = '123=east; 456=west';
// split matches into array
preg_match_all('~(\d+)=(.*?);(?=\s*(?:\d|$))~', $input, $matches);
$newArray = array();
// extract the relevant data
for ($i = 0; $i < count($matches[2]); $i++) {
$type = $matches[2][$i];
$price = $matches[1][$i];
// add each key-value pair to the new array
$newArray[$i] = array(
'type' => "$type",
'price' => "$price"
);
}
Which outputs
Array
(
[0] => Array
(
[type] => east
[price] => 123
)
)
The second item is missing as it doesn't have a semicolon on the end, i'm not sure how to fix that.
I've now realised that the numeric part of the pair sometimes contains a decimal point, and that the last string pair does not have a semicolon after it. Any hints would be appreciated as i'm not having much luck.
Here is the updated string taking into account the things I missed in my initial question (sorry):
12.30=one; two;45=three=four;600.00=five

Answer 1

You need a look-ahead assertion for this; the look-ahead matches if a ; is followed by a digit or the end of your string:
$s = '12.30=one; two;45=three=four;600.00=five';
preg_match_all('/(\d+(?:.\d+)?)=(.+?)(?=(;\d|$))/', $s, $matches);
print_r(array_combine($matches[1], $matches[2]));
Output:
Array
(
[12.30] => one; two
[45] => three=four
[600.00] => five
)

Answer 2

I think this is the regex you want:
\s*(\d+)\s*=(.*?);(?=\s*(?:\d|$))
The trick is to consider only the semicolon that's followed by a digit as the end of a match. That's what the lookahead at the end is for.
You can see a detailed visualization on www.debuggex.com.

Answer 3

You can use following preg_match_all code to capture that:
$str = '123=one; two;45=three=four;6=five;';
if (preg_match_all('~(\d+)=(.+?);(?=\d|$)~', $str, $arr))
print_r($arr);
Live Demo: http://ideone.com/MG3BaO

Answer 4

$str = '123=one; two;45=three=four;6=five;';
preg_match_all('/(\d+)=([a-zA-z ;=]+)/', $str,$matches);
echo '<pre>';
print_r($matches);
echo '</pre>';
o/p:
Array
(
[0] => Array
(
[0] => 123=one; two;
[1] => 45=three=four;
[2] => 6=five;
)
[1] => Array
(
[0] => 123
[1] => 45
[2] => 6
)
[2] => Array
(
[0] => one; two;
[1] => three=four;
[2] => five;
)
)
then y can combine
echo '<pre>';
print_r(array_combine($matches[1],$matches[2]));
echo '</pre>';
o/p:
Array
(
[123] => one; two;
[45] => three=four;
[6] => five;
)

Answer 5

Try this but this code is written in c#, you can change it into php
string[] res = Regex.Split("123=one; two;45=three=four;6=five;", #";(?=\d)");
--SJ