Re: input - E-mail address - how to check string ?

You have three conditions for email validation in your script:

$email =~ m/^[a-z0-9]@[a-z0-9]$/
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This will not allow domain extensions, so "u@d" will match, but "u@d.org" will not. Your character sets are not quantified, so they will only match a single character, "user@domain" will no longer match.

If the previous condition matched, the string cannot be empty, so the second condition is superfluous. The last one is actually equivalent to the first, because it matches what the first does and more. Since for it to even be checked the first condition must match, it's virtually the same.

Now for the solution. You need to add quantifiers to the character sets, add a dot (which need to be escaped since it matches anything otherwise) and add another set at the end. The condition could look like this:

$email =~ /^[a-z0-9]+@[a-z0-9]+\.[a-z0-9]+$/
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This will not match an empty string, since there needs to be at least one character from every character set, as well as a dot and a @.

If you don't mind allowing uppercase you could simplify it to the form:

$email =~ /^\w+@\w+\.\w+$/
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Re^2: input - E-mail address - how to check string ? by MidLifeXis (Monsignor) on Feb 25, 2015 at 14:37 UTC
see NaN's response above, and also consider a common address structure of `user@department.company.tld`. This and other more complex structures are quite common. As is stated much earlier in this thread (and learned through experience as a bitnet/usenet/campus email routing gateway admin), email addresses are not trivial. The localpart of addresses is oft horribly mangled or restricted ('-' in the $localpart converted to '_', case mangled from what is provided, etc). I treat the mangelings reasonably on my side, but the fact that they get mangled in the first place is irritating, and gives me pause when considering if the organization's IT department is up to the challenge. Since I seed addresses given to companies to identify spam leakage, I also eschew companies that restrict or mangle '-' and '+' when possible. --MidLifeXis	[reply] [d/l]
Re^3: input - E-mail address - how to check string ? by kroach (Pilgrim) on Feb 25, 2015 at 21:39 UTC
Yes, I have indeed overlooked that, thank you for pointing that out. The solution hippo came up with seems to be much better.	[reply]
Re^2: input - E-mail address - how to check string ? by Not_a_Number (Prior) on Feb 25, 2015 at 11:49 UTC
`$email =~ /^[a-z0-9]+@[a-z0-9]+\.[a-z0-9]+$/` It ain't as easy as that, unfortunately. Among multiple other problems, this rejects the millions of Brits who have an address ending in `@<whatever>.co.uk`.	[reply] [d/l] [select]