And plus OR

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

Monks,

What am I doing wrong? This does not work:

    if (($username eq "$security") && ($type ne "Check In" || $type ne
+ "Check Out")) {
[download]

But this does work:

    if (($username eq "$security") && ($type ne "Check In")) {
[download]

I need to add several more arguments for $type. If the $username is correct and 3 or 4 $types are not true, I want to print something, but I can't get it to work. I'm missing something.

Comment on And plus OR Select or Download Code

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Re: And plus OR by tybalt89 (Monsignor) on Jan 12, 2017 at 21:44 UTC
`$type ne "Check In" \|\| $type ne "Check Out"` [download] $type is always going to be not equal to one or the other	[reply] [d/l]
Re: And plus OR by AnomalousMonk (Archbishop) on Jan 12, 2017 at 21:40 UTC
What does "does not work" mean? `c:\@Work\Perl\monks>perl -wMstrict -le "my $username = 'phil'; my $security = 'phil'; my $type = 'foo'; ;; if (($username eq qq{$security}) && ($type ne 'Check In' \|\| $type ne +'Check Out')) { print qq{\$username and \$security are '$username'}; print qq{\$type is '$type'}; } " $username and $security are 'phil' $type is 'foo'` [download] Update: Please see Short, Self Contained, Correct (Compilable), Example. Update 2: After looking at tybalt89's guess about your difficulty, I think it's likely right: you're expecting the expression `$type ne "Check In" \|\| $type ne "Check Out"` to be false sometimes, and it can only be true. Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]
Re: And plus OR by Marshall (Canon) on Jan 12, 2017 at 23:23 UTC
Instead of the \|\| (or), you need && (and) in your if statement. If I understand you correctly, you want to do the "if" as long as the $username is ok, except if the $type is either of 2 conditions. Edit: I guess in other words, you want to do the "if" if the $username is ok and $type="Something Else";. `#!usr/bin/perl use strict; use warnings; my $security = "xxx"; my $username = "xxx"; my $type = "Check In"; if ($username eq "$security" and $type ne "Check In" and $type ne "Che +ck Out" ) { print "if executed, username=$username type=$type\n"; } else { print "if not executed, username=$username type=$type\n"; } __END__ if not executed, username=xxx type=Check In * This is the same thing:* if (($username eq "$security") and !( $type eq "Check In" or $type eq +"Check Out") )` [download] I show 2 different version of the "if", both do the same thing. This is called DeMorgan's theorem. Note that the "ne" becomes "eq" in the second version. I like the first version better, but your call... they are the same logically.	[reply] [d/l]
Re: And plus OR by Anonymous Monk on Jan 12, 2017 at 22:09 UTC
Search Wiki for De Morgan's Laws: `if ($username eq $security && !($type eq "Check In" \|\| $type eq "Check + Out")) { }` [download]	[reply] [d/l]
Re: And plus OR by ablanke (Monsignor) on Jan 15, 2017 at 13:52 UTC
for maintainability reasons the code could be changed to something like that: `use List::Util qw(none); my @types = ( 'Check In', 'Check Out' ); if ($username eq $security && none { $type eq $_ } @types ){}` [download]	[reply] [d/l]