buy<CODE> sub routine fixes a bug in the original game which allowed the player to purchase a few million shares when the price reached zero.</P>
<CODE>
sub buy {
    my ($portfolio, $ticker, $cash) = @_;
    my $stock_to_buy = query_user( q|What Stock would you like to buy? |);

    foreach my $stock ( keys %$portfolio ) {
        if ( $stock =~/$stock_to_buy/i ) {
            if ( $$ticker{$stock}{price} == 0 ) {
                notify_user(
                	qq|Sorry, trading has been suspended in $stock.| );
            } else {
                my $shares_to_buy = query_user(
                    qq|\n\nYou have $portfolio{$stock} shares in $stock and|,
                    qq|\$$cash\nBuy How many |,
                    qq|(max int( $cash / $$ticker{$stock}{price} ), q|) :| );
                if ( $cash < $$ticker{$stock}{price} * $shares_to_buy ) {
                    notify_user( qq|Sorry, this isn't a margin account.\n| );
                } else {
                    $$portfolio{$stock} += $shares_to_buy;
                    $cash -= $shares_to_buy * $$ticker{$stock}{price};
                }
            }
            last;
        }
    }
    return $cash;
}