Question

I’m looking for a regular expression pattern that can match adjacent characters in a string in php.

For example if I have the string “1234” I would like it to match and return

1
12
123
1234

Is this possible with regular expressions in php?

I’ve tried

$testString = '1234';
preg_match_all('/.+/', $testString, $matches);

But that just returns the entire string.

Answer 1

Using strrev trick it is possible >>

Code:

$s = '1234';
preg_match_all('/(?=(.+$)).?/', strrev($s), $m);
foreach(range(sizeof($m[1]), 0) as $i) print strrev($m[1][$i]) . "\n"; 

Output:

1
12
123
1234

See this demo.

---

However you should also go with simple solution without regex >>

Code:

$s = '1234';
foreach(range(1, strlen($s)) as $i) print substr($s, 0, $i) . "\n";

Output:

1
12
123
1234

Check this code here.