coinToss.pl

#! /usr/bin/env perl

sub toss( $ ); # prints coin toss results for $ coins

if( !defined($ARGV[0]) )
{
  # If there was no command line argument
  print "Number of coins not specified - using default number: 3\n\n";
  toss( 3 );
}
else
{
  print "Tossing $ARGV[0] coins:\n\n";
  toss( $ARGV[0] );
}

print "======================================\n";
print "   Heads = $heads\n";
print "   Tails = $tails\n\n";

if( $heads > $tails )
{
  $diff = $heads - $tails;
  print "Heads wins (by $diff).\n";
}
elsif( $tails > $heads )
{
  $diff = $tails - $heads;
  print "Tails wins (by $diff).\n";
}
else
{
  print "Draw. Tossing the decider...\n";
  toss( 1 );  
}


sub toss( $ )
{
  $heads = $tails = 0;
  $coin_limit = $_[0];
  
  for( $i = 0; $i < $coin_limit; $i++ )
  {
    # rand() function returns a value between 0 and 1
    # including 0, but excluding 1. The random seed is time().
    $x = rand( );
    if( $x >= 0.5 ) { $heads++; printf "%20.30f >= 0.5 : Heads\n", $x; }
    if( $x <  0.5 ) { $tails++; printf "%20.30f  < 0.5 : Tails\n", $x; }
  }
}