comarison synthax question

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

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Re: comarison synthax question by bobf (Monsignor) on Apr 11, 2007 at 20:41 UTC
It is most definitely not doing what you think it is. `&` is the bitwise string operator (see perlop). If you want a logical comparison, you need to use `and` or `&&` (just be aware of the difference in precedence between the two; again, see perlop). To test both variables against the regex, you need to test each of them individually. As an aside, if you didn't need the case insensitivity you could use index. I think you'll get the results you desire if you fix your second example to use `&&` instead of `&` .	[reply] [d/l] [select]
Re: comarison synthax question by Fletch (Bishop) on Apr 11, 2007 at 20:42 UTC
You're getting closer with the second, but `&&` is the boolean AND operator (`&` is the bitwise AND; see perlop for more details). And using grep might be a bit more idiomatic, especially since the numbered variable names is a common red flag that you should really be using an array instead. `my @statuses = _frobulate_status_processes( ); my $running_frobulators = grep { m/\A Running \z/xi } @statuses; if( @statuses == $running_frobulators ) { print "All processes frobulating\n"; } else { print "Only $running_frobulators of ", scalar @statuses, " running\n +"; }` [download]	[reply] [d/l] [select]
Re: comarison synthax question by thezip (Vicar) on Apr 11, 2007 at 20:47 UTC
Actually, neither will currently work, but the second option is closer to what you want to do. You'll need to use either 'and' or '&&' to conjoin the logical expressions, which must be explicitly stated as you did in the latter code. `if (($STATUS1 =~ m/^Running$/i) && ($STATUS2 =~ m/^Running$/i)) { + print "match\n"; ^^ }` [download] You could also use: `if (($STATUS1 eq "Running") && ($STATUS2 eq "Running")) { print "match\n"; }` [download] ... if you could expect the upper/lower case not to change. You've already tightened it down pretty hard with /^...$/, so a test for equality might also be appropriate. Where do you want them* to go today?*	[reply] [d/l] [select]
Re: comarison synthax question by Krambambuli (Curate) on Apr 11, 2007 at 20:41 UTC
`my $STATUS1 = "Running"; my $STATUS2 = "Sunning"; print $STATUS1 & $STATUS2, "\n";` [download] prints 'Running', as R is 0x52 and S = 0x53, but R & S = R So _no_, don't use '&' unless you know you're working on bits. I guess you might have it also like `if (lc($STATUS1) eq lc($STATUS2) and lc($STATUS1) eq 'running') {... }` [download] Why not being explicit whenever possible ?	[reply] [d/l] [select]
Re: comarison synthax question by ptum (Priest) on Apr 11, 2007 at 20:43 UTC
Well, for starters you'll probably want to use && instead of &, which is a bitwise 'and'. See perlop. Update: As to your main question, I see that others beat me to the punch. :)	[reply]


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