Hi apotheon,

I'm a fan of producing a syntax message whenever arguments to a program are expected.  That way, the user never has to guess what the program does, nor what the program expects for input.

Additionally, if you don't check to see that you DID get input, then you'll end up getting errors or "harder to track" unexpected results.

That's why I'd suggest doing an assignment to your command line variables up front, and aborting with a syntax message if the program doesn't get what it wants.  That has the additional benefit of letting you do validity checking on those variables next, as well as simplifying your code later.

Here's how I might "neaten it up" a bit: 

#!/usr/bin/perl -l

# Libraries
use strict;
use warnings;
use Getopt::Std;
use File::Basename;

our ($opt_s);
getopts('s');

# Globals
my $iam = basename $0;
my $syntax = "
    syntax:  $iam  <first number>  <second number>
 
    Your syntax message here.

";

# Command-line
(my $x = shift) or die $syntax;
(my $y = shift) or die $syntax;

# Validity checking
($x =~ /^-?\d+$/) or die "$iam:  value $x not an integer\n";
($y =~ /^-?\d+$/) or die "$iam:  value $y not an integer\n";

# Main program
if ($opt_s) {
    printf "%d\n", ($y - $x + 1) * ($x + $y) / 2;
} else {
    printf "%d\n", ($y - $x) * ($x + $y + 1) / 2;
}

[download]

To my eye, the main program is a lot easier to read now, as a result of assigning to $x and $y.  That's partly because the lines are a lot shorter, so each printf statement fits on its own, single line.

s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/

In reply to Re: a simple exercise in readability by liverpole
in thread a simple exercise in readability by apotheon

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