Regular expression extraction from JSON string in PHP

Question

I have a string in PHP which could look similar to the following:

$string = '"["1000: Person One","1001: Person 2","1002: Person Three"]"';

It is generated from a JSON Array. I need to write a regular expression to separate the JSON elements into a PHP array. I need to pull just the numbers before each colon out. I have tried the following code, with no success:

preg_match_all('/\"[^:]*:/',$string,$target_array); //No Success
preg_match_all(/\"\d*:/,$string,$target_array); //No Success

What I need is a regex which can pull any characters between a " and a :.

Of course, this leaves problems if a person's name happens to include a similar pattern. The best thing I could do would be to parse the JSON array into a PHP array. So as an alternate (and preferred) solution, a way to parse the JSON array into a PHP array would be spectacular. I have already tried to json_decode the string, but it always yields NULL.

Edit: As a curiosity, when I copy the string directly from output with no filtering and json_decode that, it converts to a PHP array perfectly.

What is wrong with json_decode? works fine for me: codepad.viper-7.com/iT2T8G You could then just loop over the array and explode on :. — Jonathan Kuhn
– Jonathan Kuhn, Commented Dec 26, 2013 at 20:14

Ahmed Siouani · Accepted Answer · 2013-12-27 12:52:18Z

1

If it is a valid JSON string, try this (the solution is safer than using regexens):

$string = '["1000: Person One","1001: Person 2","1002: Person Three"]';
$arr = json_decode($string);
$keys = array();
foreach ($arr as $value) {
  $keys[] = (int)current(explode(":", $value, 2));
}
print_r($keys); // $keys contains the numbers you want.

// output:
//  Array
// (
//    [0] => 1000
//    [1] => 1001
//    [2] => 1002
// )

Here, have a look at this: http://codepad.viper-7.com/4JVAV8

edited Dec 27, 2013 at 12:52

Ahmed Siouani

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answered Dec 26, 2013 at 20:24

Stoic

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1 Comment

Legendary_Linux Over a year ago

You won't believe me when I tell you I tried this already, but for some reason it works now, so you have my thanks.

revo · Accepted Answer · 2013-12-26 20:31:27Z

1

As Jonathan Kuhn confirmed, json_decode works fine. but you can use regular expressions too:

$string = '["1000: Person One","1001: Person 2","1002: Person Three"]';
preg_match_all('/"(.*?):\s*([^"]+)"/', $string, $matches);
print_r($matches);

Output:

Array
(
    [0] => Array
        (
            [0] => "1000: Person One"
            [1] => "1001: Person 2"
            [2] => "1002: Person Three"
        )

    [1] => Array
        (
            [0] => 1000
            [1] => 1001
            [2] => 1002
        )

    [2] => Array
        (
            [0] => Person One
            [1] => Person 2
            [2] => Person Three
        )
)

answered Dec 26, 2013 at 20:31

revo

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