Regex for matching a pattern with one length or another

Question

I need to match a pattern with strictly 10-symbols length OR 12 (not 11). So this won't work

[0-9]{10,12}

Can I write something more simple than

([0-9]{10}|[0-9]{12})

?

Please specify the language/regex flavour you use. Different flavours make different things possible. — Denys Séguret
– Denys Séguret, Commented Feb 18, 2014 at 16:34

Denys Séguret · Accepted Answer · 2014-02-18 16:30:10Z

3

You can use ? to set a char or group as optional :

\d{10}(\d\d)?

Don't forget to match start and end if that's the whole regex :

^\d{10}(\d\d)?$

answered Feb 18, 2014 at 16:30

Denys Séguret

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2 Comments

This is correct for this regex, but the pattern can be more complicated than just numbers

Then use the more complicated pattern, the important point is the ? to make an optionnal group.

Piyuesh · Accepted Answer · 2014-02-18 16:40:48Z

1

Something like this may work..

(pattern)((\1){11}|((\1){9}))

I've just used backreference in php (\1)....

answered Feb 18, 2014 at 16:40

Piyuesh

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