How can I build this simple regex?

Asked Nov 08 '19 at 17:19

Active Nov 08 '19 at 17:21

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I need to build a regex to match: lowercase letters, numbers, underscore and length should be between 4 and 16 characters (both included);

/[a-z0-9_]{4,16}/g

This should be strait on, but my code is braking (in the context of the challenge I'm in). Even though is passing on RegExr.com.

It's hard to see whats wrong because its giving me the right match online. I've tried to see some tutorials but I believe that the regex is correct, although I can't figure whats wrong...

edited Nov 08 '19 at 17:21

asked Nov 08 '19 at 17:19

Tiago Ruivo

can you give example on what is not working ? maybe some cases to try. – Nicolas Nov 08 '19 at 17:21
2

Perhaps use anchors `^[a-z0-9_]{4,16}$` – The fourth bird Nov 08 '19 at 17:21
is failing on these two:'Hasd_12assssssasasasasasaasasasasas', 'asd43 34' – Tiago Ruivo Nov 08 '19 at 17:22
It needs to be anchored, otherwise it will match a substring. – Barmar Nov 08 '19 at 17:23
@TiagoRuivo the second example fails correctly, there is a space which is not a character you mentioned – Fabrizio Calderan loves trees Nov 08 '19 at 17:24
^[a-z0-9_]{4,16}$ this did the trick... Of course, it was so obvious, when you are trying to match a password... – Tiago Ruivo Nov 08 '19 at 17:25
thanks guys... I've sorted it!!!! – Tiago Ruivo Nov 08 '19 at 17:26

How can I build this simple regex?

0 Answers0