Sorry about my original post,
Now the problem is, I know defined and how to use it but the problem here is, if those variable are "undef" do some thing else,
if (defined($key))
{
....
}
but is there any thing like this
if (undefined($key))
{
....
}
Any suggestion???
You have not programmed much, have you? The perlop manpage does not hide how to invert logic expressions. See logical not for how to execute something if a condition is not true.