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Re^2: If statement not working

by andye (Curate)
on Aug 24, 2012 at 15:09 UTC ( #989565=note: print w/ replies, xml ) Need Help??


in reply to Re: If statement not working
in thread If statement not working

Use of "elsif" or hash tables don't seem to go to the point.

Actually either of those approaches does solve the problem, which is (if I'm understanding the OP correctly) that:

The OP thinks that the 'else' clause will be executed if NONE of the 'if' statements match, whereas actually the 'else' clause will be executed whenever the FINAL 'if' statement fails to match.

i.e. OP's intention was

if () {} elsif () {} elsif () {} else {}
but OP has got the syntax wrong and actually coded
if (a) {}; if (b) {}; if (c) {}; if (d) {} else {default()};
where even if one of a, b or c is true then default() is still executed (and overwrites the variable) so long as d is false.

IIU the OP correctly.


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Re^3: If statement not working
by Marshall (Prior) on Aug 26, 2012 at 01:17 UTC
    I see what you mean, that this is a "dangling else" clause.

    I guess something like:

    $trimmedcolr = $colr; $trimmedcolr = 'BB' if $colr eq 'baby blue'; $trimmedcolr = 'BP' if $colr eq 'baby pink'; $trimmedcolr = 'DB' if $colr eq 'dark blue'; $trimmedcolr = 'DP' if $colr eq 'dark purple'; $trimmedcolr = 'HP' if $colr eq 'hot pink'; $trimmedcolr = 'LP' if $colr eq 'light purple';
    would have worked although the hash based solutions in this thread are probably more efficient. BTW, I have no problem with this trailing "if" syntax in a situation like this were the intent and readability is very clear.

    The "why" question wasn't asked. However since Perl is so good at processing strings, I would suggest that translating an easily understandable string into a shorter more cryptic string is usually just not necessary or advisable.

    I would not do this translation without a good reason. One reason might be that this program talks to something else that only understands the two letter abbreviations, however in that case, the default of not abbreviating the color doesn't appear to make sense. Making this a subroutine and returning an error in the case of an unknown color might make sense. I don't know what this "abbreviate it if you can" idea accomplishes.

    Update:
    Without a good reason, I wouldn't do this, but consider this:

    #!/usr/bin/perl -w use strict; my @colors = ( 'baby blue', 'baby pink', 'dark blue', 'dark purple', 'hot pink', 'light purple', 'wild green', 'crazy yellow', 'wild crazy purple', 'deep purple'); foreach (@colors) { print getColorAbreviation($_),"\n"; } # The translation algorithm appears to be straight- # forward, so a table independent translation is # possible ... Of course 'dark purple' and 'deep purple' # would translate into the same thing, but maybe that is # ok? This is application dependent. sub getColorAbreviation { my $color = shift; #like: 'wild crazy purple' $color = uc $color; my @FirstCaps = $color =~ /(\w)\w+/g; return @FirstCaps; #like: WCP } __END__ BB BP DB DP HP LP WG CY WCP DP

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