Split an alphanumeric string after each sequence of numbers

Question

I have a series of strings in the form of

10a99b5c
55
2a3b1
g

How can I split the string by the characters (which always appears as a single character between numbers or in the beginning/end of the string)

array([0] => 10a99b5c, [1] => 10, [2]=> a99, [3] => b5, [4] => c),
array([0] => 55, [1] => 55),
array([0] => 2a3b1, [1] => 2, [2] => a3, [3] => b1),
array([0] => g, [1] => g),

The output format is not important, I can handle, I just have no idea what sort of regex pattern can do the trick (even a hint is sufficient).

I do this with preg_replace_callback where I use the digits found for each character for a set of calculations.

@Nicolas as I mentioned, I am looking for a hint to begin with. I have no clue what can match the existing and missing elements. — Googlebot
– Googlebot, Commented Jan 28, 2020 at 18:03
@Luuk Wonderful, I got what I needed. If you post it as an answer, an accepted answer may help other people too. Thanks! — Googlebot
– Googlebot, Commented Jan 28, 2020 at 18:12

jspit · Accepted Answer · 2020-01-28 18:56:43Z

1

Try this:

$input = ['10a99b5c','55','2a3b1','g'];
$regEx = '~([a-z]\d*)~';

foreach($input as $str){
  $res[] = preg_split($regEx,$str,-1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
}
echo '<pre>';
var_export($res);

The result for the examples above:

array (
  0 => 
  array (
    0 => '10',
    1 => 'a99',
    2 => 'b5',
    3 => 'c',
  ),
  1 => 
  array (
    0 => '55',
  ),
  2 => 
  array (
    0 => '2',
    1 => 'a3',
    2 => 'b1',
  ),
  3 => 
  array (
    0 => 'g',
  ),
)

answered Jan 28, 2020 at 18:56

jspit

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Comments

Luuk · Accepted Answer · 2020-01-28 18:12:46Z

1

The regular expression:

/[a-z]*[0-9]*/

[a-z] will match any (lower-case) character
- zero, or more times
[0-9] will match a number
- zero, or more times

https://regex101.com/r/Ox4yUh/1

answered Jan 28, 2020 at 18:12

Luuk

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2 Comments

Nicolas Over a year ago

Please note that this regex will also match aaaaaaa10 i'm not sure if that's what you were looking for

Luuk Over a year ago

This Googlebot is only interested in an answer, not in the why...., so who cares... 😁 But indeed the first '*' should be a '?'.

mickmackusa · Accepted Answer · 2023-10-21 00:35:59Z

Your task is simple, split on the zero-width position after each sequence of numbers.

$array = preg_split('/\d+\K/', $string, 0, PREG_SPLIT_NO_EMPTY);

Match the digits with \d+, then release them with \K so that the numbers are not "consumed" during the explosion.

I'll bundle your four sample strings into an array of test strings.

Code: (Demo)

$strings = [
    '10a99b5c',
    '55',
    '2a3b1',
    'g',
];

var_export(
    array_map(
        fn($string) => preg_split('/\d+\K/', $string, 0, PREG_SPLIT_NO_EMPTY),
        $strings
    )
);

Output:

array (
  0 => 
  array (
    0 => '10',
    1 => 'a99',
    2 => 'b5',
    3 => 'c',
  ),
  1 => 
  array (
    0 => '55',
  ),
  2 => 
  array (
    0 => '2',
    1 => 'a3',
    2 => 'b1',
  ),
  3 => 
  array (
    0 => 'g',
  ),
)

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