I assume that by "letters", you mean only a-zA-Z, and not äöü for example. Then it's easy - just use a negation in your character class:

$param =~ s/[^a-zA-Z0-9_]//g;

[download]

But I'm not sure what kind of safety that buys you.

In reply to Re: Strip utf-8 dangerous url chars by Corion
in thread Strip utf-8 dangerous url chars by AlfaProject

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