--- Matthew Harrison <[EMAIL PROTECTED]> wrote:
> i need to say something like
> if $username = "" then ...
>
> where "" is literally nothing. i want to match it ONLY if the variable is
> totally empty.
>
> this is my first experience with regex so what should this be?
>
> --
> Matthew Harrison
Brett had a good response ( ! $username ) and I though I could add a couple of
comments.
When using a conditional, ("if", "unless", "while", etc.), be aware that you should
not use an
assignment operator (the "="). Instead, you should generally use "==" or "!=" for
numbers and
"eq" or "ne" for strings (if you turn on warnings, Perl is usually good about letting
you know
what's going on). So, for your above example, if you wanted to check to see if the
username is
"Ovid", you could do this:
if ( $username eq "Ovid" ) {
...
}
However, there's a little trick you can use that can help you avoid some of these
bugs. Reverse
the operands. Then, if you accidentally use the assignment operator "=":
if ( "Ovid" = $username ) {
...
}
This won't even compile because you can't assign a variable ($username) to a string
literal
("Ovid"). If you have the operands in the traditional order and don't turn on
warnings, Perl will
silently assign "Ovid" to $username, evaluate the entire expression as true, and
execute the
contents of the inner block. This is usually want you *don't* want.
Cheers,
Curtis "Ovid" Poe
=====
"Ovid" on http://www.perlmonks.org/
Someone asked me how to count to 10 in Perl:
push@A,$_ for reverse q.e...q.n.;for(@A){$_=unpack(q|c|,$_);@a=split//;
shift@a;shift@a if $a[$[]eq$[;$_=join q||,@a};print $_,$/for reverse @A
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