On 3/9/02 1:46 PM, Scot Robnett <[EMAIL PROTECTED]> wrote:
Hi Scot,
> I'm trying to do a simple verification of an e-mail address format. I want
> to require:
>
> - 1 or more alphanumeric characters
> - followed by "@"
> - followed by 1 or more alphanumerics
> - followed by a dot
> - followed by 2-4 alphanumerics.
> (for example, .tv, .com, .info)
What about things like ".co.uk"? And what about things like
<[EMAIL PROTECTED]>? I'm not that well-versed in what makes
an email address valid, but I'm sure more than a few valid email addresses
will be rejected by the above requirements.
> If the string doesn't fit these requirements, then I send them back to the
> form to re-enter the address. The problem is that using the code below, the
> program complains even when the address *is* formatted properly. Any ideas
> how I could reformat the expression better?
Yes.
> ##########################################################
>
> if(($email !=~ /\w+[@]\w+\.\w{2}/) or ($email !=~ /\w+[@]\w+\.\w{3}/)
> or ($email !=~ /\w+[@]\w+\.\w{4}/))
> {
> print "Improperly formatted e-mail address! Please use your browser\'s back
> ";
> print "button and make sure the e-mail address is entered correctly. ";
> }
>
> ##########################################################
First off, I'd recommend reading through the "pattern matching" section of
the Camel Book (Programming Perl, by Larry Wall, et al, published by
O'Reilly) again. There's a lot to learn.
Now, a slightly better-working version of the code above:
##### CODE #####
unless($email =~ /^\w+(\.\w+)*\@\w+(\.\w+)*\.\w{2,4}\z/){
# error stuff
}
else{
# email-ok stuff
}
##### END CODE #####
to examine that regex:
^\w+(\.\w+)*\@\w+(\.\w+)*\.\w{2,4}\z
^ = the beginning of the string
\w+ = one or more word chars
(\.\w+)* = any number ("any number" includes zero) of sets of a dot and one
or more word chars
\@ = @ sign
\w+ = one or more word chars
(\.\w+)* = one or more word chars followed by any number of sets of a dot
and one or more word chars
\. = a dot
\w{2,4} = one or more word chars
\z = the end of the string
I am NOT, however, saying that this regex necessarily matches all valid
email addresses, or that it screens out all invalid ones. It doesn't. And
nothing prevents users from entering something like "[EMAIL PROTECTED]".
hth,
--
Michael
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