I need someone to check my logic on this script. I am trying to simulate the net win/loss resulting from 100 games of craps. In this script, a passline bet is always made, and if there is no craps on the comeout roll, a 1X odds bet is made before the next roll. Those are the only bets. If you don't know how craps works, check out http://thewizardofodds.com/game/craps.html and read the intro, and about "the passline" and "taking the odds". It's simple and only a couple of paragraphs.

The reason I think something is wrong, is because when I simulated just 100 trials, there were a number of identical net win/loss results that occured twice. Is my logic, or random number generation the problem? THANKS! 

#!/usr/bin/perl

use Math::Random;
use DBI;
$username = "username";
$password = "password";
$database = "database";
$dbh = DBI->connect("DBI:mysql:$database", $username, $password);
for($k=1;$k<=100;$k++) {
$netwinnings = 0;
$counttwos = 0;
for($i=1;$i<=100;$i++) {
$winnings = 0;
$gameover = 0;
$numrolls = 0;
while($gameover == 0) {
$numrolls++;
##if($numrolls == 2) { print "THE POINT IS $roll\n"; }
$roll = rolldice();
##print "ROLL #$numrolls $roll\n";
if($numrolls == 1) {
$point = $roll;
if($roll == 7 || $roll == 11) {
$gameover = 1;
$winnings += 1;
##print "WIN $winnings\n\n";
} elsif($roll == 2 || $roll == 3 || $roll == 12) {
$gameover = 1;
$winnings -= 1;
##print "LOSE $winnings\n\n";
}
} else {
if($roll == $point) {
$gameover = 1;
if($roll == 6 || $roll == 8) {
$gameover = 1;
$winnings += 1.2 + 1;
##print "WIN $winnings\n\n";
} elsif($roll == 5 || $roll == 9) {
$gameover = 1;
$winnings += 1.5 + 1;
##print "WIN $winnings\n\n";
} elsif($roll == 4 || $roll == 10) {
$gameover = 1;
$winnings += 2 + 1;
##print "WIN $winnings\n\n";
}
} elsif($roll == 7) {
$gameover = 1;
$winnings -= 2;
##print "LOSE $winnings\n\n";
}
}
}
$winnings = sprintf "%.2f", $winnings;
$netwinnings += $winnings;
$netwinnings = sprintf "%.2f", $netwinnings;
}
$sth = $dbh->prepare("SELECT value,qty FROM craps WHERE value = $netwi
+nnings");
$sth->execute();
($value,$qty) = $sth->fetchrow_array();
##print "\n\n$value - $netwinnings\n\n";
if($value == $netwinnings) {
$sth = $dbh->prepare("UPDATE craps SET qty = qty + 1 WHERE value = $ne
+twinnings");
$sth->execute();
} else {
$sth = $dbh->prepare("INSERT INTO craps VALUES($netwinnings,1)");
$sth->execute(); 
}
print "NET WIN $netwinnings\n";
}
$dbh->disconnect;

sub rolldice() {
$d1 = random_uniform_integer(1,1,6);
$d2 = random_uniform_integer(1,1,6);
$roll = $d1 + $d2;
return $roll;
}

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In reply to check my logic & a random number issue by rmckillen

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