[Tutor] Amazing power of Regular Expressions...
kent37 at tds.net
Sun Nov 5 16:02:56 CET 2006
Alan Gauld wrote:
> But I sure agree with it. The problem with Regex is that they can
> be just a bit too powerful. To cite another programming proverb,
> this time by Bjarne Stroustrup I think:
> "C makes it easy to shoot yourself in the foot;
> C++ makes it harder, but when you do,
> it blows away your whole leg."
> Regex can be like that too.
I guess it's time to trot out the famous quote of Jamie Zawinsky:
> Some people, when confronted with a problem, think
> “I know, I'll use regular expressions.” Now they have two problems.
In this case I think regex is not the best solution. A better way to
validate a date is to try to use it as a date. The regex
'\d\d/\d\d/\d\d\d\d' accepts all kinds of non-dates such as 99/99/9999,
not to mention accepting US format dates such as 12/25/2006 when you
want 25/12/2006. I would use
# it's a valid date
# not a valid date
which at least restricts the input to something that is a valid date,
though it won't detect that a user typed 11/5/2006 when they mean 5/11/2006.
Regular expressions are an extremely powerful and useful tool that every
programmer should master and then put away and not use when there is an
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