{ xTurtle Tutorial Example #2: Variables.

  A variable is a name that can be used
  to hold a value.  Variables must be
  declared before they are used.  A 
  variable can be assigned a value with
  an assignment statement.  Variables
  and functions can be used to compute
  values from complex expressions
  such as 3 * sin(x+3).
}

DECLARE x, y  { Allows you to use the
                variables named x and y. }
                
x := 2  { Assignment statement,
          puts the value 2 into
          into the variable x. }
          
y := 2*sqrt(x) { Computes sqrt(2), multiplies it
                 by 2, and assigns the resulting
                 value to y.  Sqrt computes
                 the square root.  There are
                 other predefined functions. }

forward(x)  { Variables can be used in commands. }
turn(-135)  { Negative turn rotates the turtle
              in a clockwise direction. }
forward(y)
turn(135)
forward(x)  { These commands have 
              drawn a Z-shape. }


DECLARE Rate { Declares another variable.
               They don't have to be declared
               at the start of the program.
               Names can be any number of
               characters. }

Rate := 0.07  { Decimal numbers are OK. }

DECLARE money, interest  { More variables. }
money := 1000
interest := Rate * money

PenUp
MoveTo(-8,8)
PenDown

DrawText("Interest on $#money is #interest.")
  { The value of a variable can be included
    in a string.  Just include the
    character #, followed by the name of
    the variable.  When the string is
    actually printed, the value of the
    variable is shown. }
    
x := random { Assign a random value in the
              range 0.0 to 1.0 to x.  The
              value will be different every
              time the program is run.
              Note that x was already declared,
              so I don't have to declare it
              again.  In fact, it would be
              an error to do so. }
              
y := randomInt(100)  { y is assigned a
                       random integer in
                       the range 1 to 100. }
                       
DrawText("Here's a random number: #x")
DrawText("Here's a random integer: #y")