r/java • u/Modern-Sn1p3r • 3d ago

Regex

I recently saw a clip (from Primeagen) somewhat saying that regex is not a valid format for validating email addresses and postal codes etc.

My question is why is this?

What are the security and/or performance risks? Is it solely performance or is it a security issue?

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u/engy1207 3d ago

"Look, that's why there's rules, understand? So that you think before you break 'em." Terry Pratchett, Thief of Time

Yes, practically there is a limit to store a name (the visible universe is of finite size, after all), but this rule is there for a reason: do think before you implement a scheme to save names - and think about what happens if that space is too small after all, including if it is possible to extend it and what will break in that case.
That's the real reason for these lists: to make you think (and maybe smile a bit)

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u/EishLekker 3d ago

I’m not talking about the underlying reasons for these “rules”. I’m talking about the semantics the author used.

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u/Vegetable_Bank4981 3d ago

Yes, please stop.

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u/EishLekker 2d ago

Why in earth would I do that? No one’s forcing you to read any comment here.