Bug with Turing?

[Fozmik]

This is a program I've been working on for a while and it is supposed to give ideal change for a twenty dollar bill. It works great for most numbers except for when the price is like 1.05, 2.05, 3.05, 4.05, 5.05 etc, or amounts with cents in values of .10 - .30 and .70 - .90 (this is like $0.10, $0.20, $.30, $1.10, $1.90). Also it doesn't work for numbers ending in .98.

Something interesting to note is that the problem only occurs once it's finished giving change for tens, fives, toonies, loonies and quarters and starts doing dimes and downward. This is where things happen like the program gives 9 pennies instead of 10, and rather than giving 2 dimes it would give a nickel and 5 pennies (in some cases it falls short and gives 4).

To fix the problem I tried using the break function and output the Change variable amount every so often and sometimes the variable ends up being 0.05 and it is supposed to mod itself by 0.05 to end at 0 (and 0 pennies for exact change), but turing chooses to ignore this line and leaves the Change variable at 0.05. In the output window this looks like 5 extra pennies, and also not in the form of a nickel.

Is this a problem with turing or is it because I am using div and mod in the wrong places?

code:

setscreen ("graphics") var price : real var change : real var change2 : real var pennies : real var answer : array char of boolean var window : int var finished : boolean := false var location : boolean := false var medarial : int medarial := Font.New ("arial:12") window := Window.Open ("position:center;center,graphics:250;260") Font.Draw ("This program calculates the most", 0, maxy - 14, medarial, black) Font.Draw ("ideal change for a twenty dollar bill.", 0, maxy - 34, medarial, black) loop     loop         loop             if location = false                     then                 Font.Draw ("The total cost of the item(s)", 0, maxy - 74, medarial, black)                 Font.Draw ("purchased is:", 0, maxy - 94, medarial, black)                 Font.Draw ("$", 0, maxy - 122, medarial, black)                 locate (7, 2)                 get price                 location := true             else                 Font.Draw ("The total cost of the item(s)", 0, maxy - 14, medarial, black)                 Font.Draw ("purchased is:", 0, maxy - 34, medarial, black)                 Font.Draw ("$", 0, maxy - 68, medarial, black)                 locate (4, 2)                 get price             end if             if price > 20                     then                 cls                 Font.Draw ("The amount must be equal to", 0, maxy - 14, medarial, black)                 Font.Draw ("or smaller than $20.", 0, maxy - 34, medarial, black)                 location := false             elsif price <= 20                     then                 exit             end if         end loop         cls         if price = 20                 then             Font.Draw ("No change.", 0, maxy - 14, medarial, black)             exit         else             Font.Draw ("The cost is $", 0, maxy - 14, medarial, black)             locate (1, 10)             put price : 0 : 2             Font.Draw ("Your change is $", 0, maxy - 32, medarial, black)             locate (2, 13)             put 20 - price : 0 : 2         end if         change := 20 - price         if change >= 10                 then             if change div 10 > 1                     then                 Font.Draw (realstr (change div 10, 1), 0, maxy - 65, medarial, black)                 Font.Draw ("ten dollar bills.", 12, maxy - 65, medarial, black)                 change := change mod 10             else                 Font.Draw ("1 ten dollar bill.", 0, maxy - 65, medarial, black)                 change := change mod 10             end if         else             Font.Draw ("No ten dollar bills.", 0, maxy - 65, medarial, black)         end if         if change >= 5                 then             if change div 5 > 1                     then                 Font.Draw (realstr (change div 5, 1), 0, maxy - 85, medarial, black)                 Font.Draw ("five dollar bills.", 12, maxy - 85, medarial, black)                 change := change mod 5             else                 Font.Draw ("1 five dollar bill.", 0, maxy - 85, medarial, black)                 change := change mod 5             end if         else             Font.Draw ("No five dollar bills.", 0, maxy - 85, medarial, black)         end if         if change >= 2                 then             if change div 2 > 1                     then                 Font.Draw (realstr (change div 2, 1), 0, maxy - 105, medarial, black)                 Font.Draw ("toonies.", 12, maxy - 105, medarial, black)                 change := change mod 2             else                 Font.Draw ("1 toonie.", 0, maxy - 105, medarial, black)                 change := change mod 2             end if         else             Font.Draw ("No toonies.", 0, maxy - 105, medarial, black)         end if         if change >= 1                 then             if change div 1 > 1                     then                 Font.Draw (realstr (change div 1, 1), 0, maxy - 125, medarial, black)                 Font.Draw ("loonies.", 12, maxy - 125, medarial, black)                 change := change mod 1             else                 Font.Draw ("1 loonie.", 0, maxy - 125, medarial, black)                 change := change mod 1             end if         else             Font.Draw ("No loonies.", 0, maxy - 125, medarial, black)         end if         if change >= 0.25                 then             if change div 0.25 > 1                     then                 Font.Draw (realstr (change div 0.25, 1), 0, maxy - 145, medarial, black)                 Font.Draw ("quarters.", 12, maxy - 145, medarial, black)                 change := change mod 0.25             else                 Font.Draw ("1 quarter.", 0, maxy - 145, medarial, black)                 change := change mod 0.25             end if         else             Font.Draw ("No quarters.", 0, maxy - 145, medarial, black)         end if         if change >= 0.10                 then             if change div 0.10 > 1                     then                 Font.Draw (realstr (change div 0.10, 1), 0, maxy - 165, medarial, black)                 Font.Draw ("dimes.", 12, maxy - 165, medarial, black)                 change := change mod 0.10             else                 Font.Draw ("1 dime.", 0, maxy - 165, medarial, black)                 change := change mod 0.10             end if         else             Font.Draw ("No dimes.", 0, maxy - 165, medarial, black)         end if         if change = 0.05                 then             if change div 0.05 > 1                     then                 Font.Draw (realstr (change div 0.05, 1), 0, maxy - 185, medarial, black)                 Font.Draw ("nickels.", 12, maxy - 185, medarial, black)                 change := change mod 0.05             else                 Font.Draw ("1 nickel.", 0, maxy - 185, medarial, black)                 change := change mod 0.05             end if         else             Font.Draw ("No nickels.", 0, maxy - 185, medarial, black)         end if         if change >= 0.01                 then             if change div 0.01 > 1                     then                 Font.Draw (realstr (change div 0.01, 1), 0, maxy - 205, medarial, black)                 Font.Draw ("pennies.", 12, maxy - 205, medarial, black)             else                 Font.Draw ("1 penny.", 0, maxy - 205, medarial, black)             end if         else             Font.Draw ("No pennies.", 0, maxy - 205, medarial, black)         end if         exit     end loop     Font.Draw ("Press ' n ' to exit the program.", 0, maxy - (maxy - 3), medarial, black)     Font.Draw ("Press ' y ' to receive change again.", 0, maxy - (maxy - 23), medarial, black)     loop         Input.KeyDown (answer)         if answer ('y')                 then             cls             exit         elsif answer ('n')                 then             finished := true             exit         end if     end loop     exit when finished end loop Window.Close (window)