Require some subtle wisdom

jailbird has asked for the wisdom of the Perl Monks concerning the following question:

First, some background. This is part of a script I am writing to make a user in the system, and an SQL database. It makes users fine, but I haven't began on the SQL part yet.

This is part of a particular subroutine I wrote to get the password for the user from the admin- I know it is not perfect but this is a work in progress.

do
{
    print "Enter password: ";
    chomp ($pw1 = <STDIN>);
    print "Enter it again, I don't trust you: ";
    chomp ($pw2 = <STDIN>);
} while (($pw1 ne $pw2) && ($pw1 ne ""));

This piece of code works fine- my question is this: at first it did not function correctly, regardless of what was entered both times the first pw would be passed back. Changing to ne from != fixed it up. I thought they were the same thing, whats up?

-r0bb

Comment on Require some subtle wisdom

Replies are listed 'Best First'.
Re: Require some subtle wisdom by kilinrax (Deacon) on Jan 22, 2001 at 17:53 UTC
'`ne`' compares them as strings, '`!=`' as numbers. Any non-numeric string evaluates to zero, numerically, hence '`!=`' would (nearly) always claim two strings were equal.	[reply]
Re: Require some subtle wisdom by clemburg (Curate) on Jan 22, 2001 at 17:56 UTC
Perl has different operators for comparing strings and for comparing numbers. `ne` is for strings, and `!=` is for numbers. See `perldoc perlop` on your favorite command line. Christian Lemburg Brainbench MVP for Perl http://www.brainbench.com	[reply] [d/l] [select]
Re: Require some subtle wisdom by tame1 (Pilgrim) on Jan 22, 2001 at 22:16 UTC
!= and = are designed around numbers. Your text was just that - text. ne, eq and such are designed around text. So, when comparing numbers, use math symbols. When using text, use words. What does this little button do . .`<Click>`; "USER HAS SIGNED OFF FOR THE DAY"	[reply] [d/l]
Re: Require some subtle wisdom by repson (Chaplain) on Jan 23, 2001 at 04:56 UTC
I'm not sure your while condition does what you want. You probably meant `while (($pw1 ne $pw2) \|\| ($pw1 eq ""))` I'd probably make that `until ($pw1 && ($pw1 eq $pw2))` Just a bit clearer, and correct.	[reply] [d/l] [select]