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Hypertexknowlogy

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Wait , WAIT !!What's that word ? ( Class Notes ( without definitions ) )
Monday October 16 , 2000
 
O-O Architecture
LineOfSquares
{
/ /instance variable
    private int nrSquares;
    private double edgeLength;
/ /constructor
    public LineOfSquares ()
    {
        IO.print ( ``How many squares?   ``);
        nrSquares = IO.read_int ();
        IO.print ( ``Area of figure?   );
        double areaOfFigure = IO.read_double ();
        double areaOfSquare = areaOfFigure /nrSquares;
        edgeLength = Math.sqrt (areaOfSquare);
    }
    public double perimeter ()
    {
        return edgeLength * eeCount ();
    }
    private int eeCount ()
    {
        return (2 * nrSquares) + 2;
    }
}
Remark
Characteristics of the imperative style are...
  1. Binding Commands (Assignment statements)
  2. conditional commands (selectors)
  3. repetition commands
  4. IO commands
Program to read two integers and display the larger of the two.
int a = IO.read_int ();
int b = IO.read_int ();
if (a > b)
{
    IO.println (a);
}
else
{
    IO.print (b);
}
Program to read two inegers and display the word ``ok'' if they are not equal.
int a = IO.read_int ();
int b = IO.read_int ();
if (a!   = b)
{
    IO.println ( ``Ok'');
}
multiway if
read one integer and display
  • zero
  • negative
  • positive
depending on the integer
int a = IO.read_int ();
if (a > 0)
{
    IO.println ( ``Positive'');
}
else if (a < 0)
{
    IO.println ( ``Negative'');
}
else
{
    IO.println ( ``Zero'');
}
Read 3 integers and display them in order,  low to high.   Way 1:   nested if.
/ /Read the integers
    int a = IO.read_int ();
    int b = IO.read_int ();
    int c = IO.read_int ();
    if (a < b)
    {
        if (a < c)
        {
            IO.println (a);
            if (b < c)
            {
                IO.println (b);
                IO.println (c);
            }
            else
            {
                IO.println (c);
                IO.println (b);
            }
        }
    }
Way 2:   Abstarction
if (less (a,  b,  c))
{
    IO.println (a + ````+ b + ````+ c);
}
else if (less (a,  c,  b))
{
    IO.println (a + ````+ c + ````+ b);
}
else if (less (b,  a,  c))
{
    IO.println (b + ````+ a + ````+ c);
}
...   3 more cases
static private boolean less (int,  int y,  int z)
{
    if (x < y)
    {
        if (y < z)
        {
            return true
        }
    }
        return false;
}
The boolean data type
name:   boolean
values:   true false
Operators
& & (AND)
| | (OR)
!   (NOT)