I’m using PHP 8.2.11 on Mac Sonoma 14.5.

My code is:

$cost = '£45.56–34.90';
$matches = array();
$found = preg_match(
  '/£?.*£?/',
  $cost,
  $matches
);

I’d expect preg_match() to return 1, indicating a match, and to populate $matches like this:

array (
  0 => '£45.56–34.90',
)

However, $found === 0 and $matches is empty.

I tested this on https://regex101.com, which matched as I expected.

If I change my code so that $cost === '£45.56–£34.90' (with a second pound sign added), then $found === 1 and $matches is populated as:

array (
  0 => '£45.56–£34.90',
)

If I change my code so that $cost === '£45.56–34.90' and the pattern is '/£?.*£?/g', then $found === false.