PERL regex for discord id that ends after 4th digit

Question

I tried using this which appears to work..

^.*#[0-9]{4}$

test#1234

Except this also is accepted as valid input.

test#1234 #1234

How do I go about making it so that after the 4 digits no other characters will be accepted without hindering the initial match?

Thanks in advance for the help.

Answer 1

I'd use:

$string =~ /^\D+#\d{4}$/

Where \\D stands for any character that is not a digit.

Answer 2

One approach would be to use a negative lookahead which asserts that a #1234 pattern does not occur after matching the first one:

^[^#]*#[0-9]{4}(?!.*#[0-9]{4}).*$

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