Perl allows to use arithmetics on string

Here's the code: 
#!/usr/local/bin/perl -w

use strict;


sub step_over_desert # () I won't repeat this mistake anymore!!!
{
    print "Tsock...\n";
}


sub cover_the_distance # () I won't repeat this mistake anymore!!!
{
    my ($me, $desert_width, $max_spit_distance, $num_legs, $last_name,
+ $day_phone, $days_without_water) = @_;

    my $num_steps=0;
    while($desert_width)
   {
       my $todo = $desert_width * $num_legs;
       print "$desert_width miles remaining; $todo steps yet to do.\n"
+;

       step_over_desert();
       $desert_width--;

       $num_steps += $num_legs;
   }

    print "Steps made: $num_steps\n";
}


#cover_the_distance("strong animal", 5, 15, 4, "Mabooka", "(123)-456-7
+890", -1);
cover_the_distance("strong animal", "five thousand miles", 15, 4, "Mab
+ooka", "(123)-456-7890", -1);


1;

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Don't try it at home

Well, I recommend at the very least to redirect the output to a file:-).

Why people do this?

Again, the main reason: because it allows you. One may expect either a compile-time error or a run-time exception. But Perl allows you to shoot your own foot.
Actually, this is an obfuscated (starting to love the word) code from a real-life app. The real application would send a query over the wire to the server,
get a responce line --
-- that should look smth. like this:
200 OK 578
-- meaning " there're 578 lines yet to read from the socket,
parse this line and create a loop: 
while($numlines) {
   get_next_one(...);
   $numlines--;
   ...
}

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Well guess what? Once in 10000 times the server would get tired and send a garbled status line -- smth. like:
200 OK whatever,man

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and 
  (while "whatever,man"--)
     {....}

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will start the almost infinite loop. (Try the code above).

Solution

Be aware.
use int($n).
Ask your new hires during the inteview: "What is the result of the following operation: 
"Larry"--;

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-?.

In reply to Re^2: Example 2: incrementing "something" by Mabooka-Mabooka
in thread Common Beginner Mistakes by chromatic

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