Question

Still learning regular expression! My percentage regular expression (not respecting the 100 limit):

^(?<int>[1-9][0-9]*|[0])(?<dec>\.[0-9]+)?\%?$

This should allow:

• [1-9] start with a number different from 0. Percentage like “004.34” is not allowed.
• [0-9]* …followed by any digit in between 0 and 9
• |[0] or start with a single 0

… capturing this group as “int” group. Then:

• (?<dec>\.[0-9]+)? an optional group, where a point is allowed only when is followed by at least one digit between 0 and 9. I don’t want people to input i.e. “33.”

Assuming I’m right, testing with:

preg_match('/^(?<int>[1-9][0-9]*|[0])(?<dec>\.[0-9]+)?\%?$/i', '0.32%', $result);

Gives me this result, which is actually correct, but:

Array
(
    [0] => 0.32%
    [int] => 0
    [1] => 0
    [dec] => .32
    [2] => .32
)

how can avoid capturing the percentage “%” sign (in $result[0])?

Answer 1

It’s pretty simple really. Just change your regex to this:

/^(?<int>[1-9][0-9]*|[0])(?<dec>\.[0-9]+)?/

(Remove \%?$ from matching).

If you want to make sure that the % sign is there, but don’t want to capture it (it seems like it wouldn’t matter in this case but maybe) you can add a lookahead assertion. (?=...) Assertions make sure that pattern exists, but it doesn’t change what is matched.

/^(?<int>[1-9][0-9]*|[0])(?<dec>\.[0-9]+)?(?=%?$)/