Re: Simple add and multiply subroutines

Not that I'm disagreeing with all the errors/problems other people have pointed out, but this is really the canonical case for using a dispatch table.

#!/usr/bin/perl -w
use strict;

my $op = shift or die "You must specify an operation followed by numbe
+rs.\n";
die "Non-numeric input.\n" if grep /\D/, @ARGV;

my %perform = (
    add         =>  sub { local $" = "+"; eval "@ARGV"; },
    multiply    =>  sub { local $" = "*"; eval "@ARGV"; },
);

die "Invalid operation.\n" unless defined $perform{$op};

print $perform{$op}->();
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-- 
Human history becomes more and more a race between education and catastrophe. -- HG Wells

Comment on Re: Simple add and multiply subroutines Download Code

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Re^2: Simple add and multiply subroutines by jwkrahn (Abbot) on Apr 08, 2008 at 06:35 UTC
Dispatch table - yes, string eval - OMG NO! especially not for a beginner! Your grep test for "Non-numeric input" won't accept floating point numbers or negative numbers.	[reply]
Re^3: Simple add and multiply subroutines by oko1 (Deacon) on Apr 08, 2008 at 20:05 UTC
Nor engineering notation, nor imaginary numbers, nor Roman numerals either. It will, however, handle the integers as shown in the original request. :) String eval... OK, you're right. Easy enough to fix, and I see (behind the cut tags) that the poster just before me already did that. -- Human history becomes more and more a race between education and catastrophe. -- HG Wells	[reply]