PHP regex to match all single letters followed by numeric value in string

Question

I'm trying to get the a regex running for the following type of strings: one upper case letter followed by a numeric value. The string can consist of multiple of these letter-numeric-value combinations. Here some examples and my expected output:

A12B8Y9CC10
-> output [0 => 12, 1 => 8, 2 => 9] (10 is ignored, because there are two letters)
V5C8I17
-> output [0 => 5, 1 => 8, 2 => 17]
KK18II9
-> output [] (because KK and II are always two letters followed by numeric values)
I8VV22ZZ4S9U2
-> output [0 => 8, 1 => 9, 2 => 2] (VV and ZZ are ignored)
A18Z12I
-> output [0 => 18, 1 => 12] (I is ignored, because no numeric value follows)

I tried to reach this by the following regex using preg_match: /^([AZ]{1}\d{1,)$/

But it doesn't give the expected output. Can you please help me, how to solve this?

Thanks and best regards!

Answer 1

You may use this regex in php using preg_match_all :

preg_match_all('/(?<![a-zA-Z])[a-zA-Z]\K\d+/', $string, $matches);

Resulting in array $matches[0] to return all the matches.

RegEx Demo

RegEx Details:

• (?<![a-zA-Z]) : Make sure we don't have a letter before current position
• [a-zA-Z] : Match a letter
• \K : Reset match info
• \d+ : Match 1+ digits

Answer 2

Another variant could be using SKIP FAIL to skip matches that do not qualify.

[A-Z]{2,}\d+(*SKIP)(*FAIL)|[A-Z](\d+)

Explanation

• [AZ]{2,}\d+ Match 2 or more uppercase chars AZ and 1+ digits
• (*SKIP)(*FAIL) Use SKIP FAIL to avoid matching
• | Or
• [AZ](\d+) Match a single char AZ and capture in group 1 one or more digits

Regex demo | Php demo

The matches are the first capturing group.

$pattern = '/[A-Z]{2,}\d+(*SKIP)(*FAIL)|[A-Z](\d+)/';
preg_match_all($pattern, $string, $matches);
print_r($matches[1]);

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Or with the \K as in anubhava's answer

[A-Z]{2,}\d+(*SKIP)(*FAIL)|[A-Z]\K\d+

Regex demo | php demo