in reply to Using number "0" as an input argument

I know I can validate that the input argument was there via the following bit of code: 

chomp(my $in1 = $ARGV[0] || '');
if (defined $in1) {
    #Validate;
}

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Have you ever encountered a case where $in1 was not defined?

Maybe you want to directly check the number of arguments in @ARGV or look at what the || operator does?

Maybe the following code helps you analyze what happens better:

my $in1 = $ARGV[0] || 'user-did-not-pass-an-argument');
print $in1;

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Run the above code with

perl -w myscript.pl # no argument
perl -w myscript.pl "" # empty argument
perl -w myscript.pl 0 # zero argument
perl -w myscript.pl something-else # other argument

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Re^2: Using number "0" as an input argument
by Doozer (Scribe) on Sep 22, 2015 at 09:44 UTC

    Thanks for this. I just noticed I put "||" in my post instead of "//" which is what I have in my script. I know how they differ but thanks for pointing it out.

    I have now figured out it was a combination of using the // operator and also chomp. The code now looks something like:

    my $in1 = $ARGV[0];
chomp(my $in2 = $ARGV[1] // '');

if (defined $in1) {
   $in1 =~ s/\s+//g; # Remove all whitespace instead of chomp
   if ($in1 =~ /\D+/) {
      print "Input invalid. Only numbers are allowed\n";
   }
} else {
   print "No valid input given\n";
}

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[reply]
[d/l]
      $in1 =~ s/\s+//g;

      Although your comment suggests you are aware, I will still point out that s/\s+//g will remove all spaces, including spaces between digits/other characters, not just leading and trailing spaces.

      While unlikely to be a problem with your program, it is still possible to feed an unexpected value:

      yourprog "1 2"

      would result in $in1 being 12 and $in2 being empty

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[d/l]
[select]

      This is why you should copy/paste code instead of retyping it in your post.

      Both more accurate and faster as well! :)

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