Lecture 16 – October 19^th

Exam will be next Thursday, October 26^th during the regular class period in the lab. It will be a paper exam. It may include writing code but you will not use the computer to do this. Please try to come early. My exams are usually long and I will come at 9:15 (when the previous class ends) and you may begin as soon as you get here. You will need to finish by the end of the class period.

Submission deadline for you Queue programs has been extended to 9pm tonight (October 19^th) without penalty. After that it will be counted late and you will lose 10 points per day. It will be graded over the weekend so if you don’t turn it and the folder in by noon tomorrow, you may not get it back graded before the exam.

The first thing we did in class today was to download the generic swap specification and implementation and the skeleton of the program to use the generic and complete the skeleton.

First we tested it with integers.

Then we tested it with characters.

Then we tested it with floats

Then we tested it with fixed length strings

Then we tested it with records

Subtype myString is String(1..5) -- example of subtype declaration

With ada.float_text_io; -- is the with clause for floating point numbers

Procedure printFloat is

Value : float;

Begin

Value := 62.367;

-- to avoid exponential notation in printout of floating point number use

ada.float_text_io.put ( num => value, fore => 5, aft => 3, exp => 0);

end printFloat;

We talked abstractly about how we could modify our Stack packages so that they could handle stacks of floats, characters, strings or records instead of just integers.

Here is the original stack specification

Box #1

WITH ada.integer_text_io;

PACKAGE stack IS

StackFull : exception; -- added to original specification

StackEmpty : exception; -- added to original specification

TYPE myArrayType IS ARRAY (1..20) of integer;

TYPE aStack IS RECORD

anArray : myArrayType;

Top : integer;

END RECORD;

PROCEDURE makeEmpty (someStack : IN OUT aStack;

PROCEDURE push (someStack :IN OUT aStack;

someValue : IN integer);

PROCEDURE pop (someStack : IN OUT aStack;

someValue : OUT integer);

FUNCTION isFull (someStack : IN aStack) RETURN boolean;

FUNCTION isEmpty (someStack : IN aStack) RETURN boolean;

PROCEDURE peek (someStack : IN aStack;

someValue : OUT integer); -- could be a function

END stack;

An outline of the necessary changes to the specification to make it generic is here

GENERIC

TYPE Element IS PRIVATE;

PACKAGE Stacks_Generic IS

TYPE aStack (Capacity: Positive) IS LIMITED PRIVATE;

StackFull : EXCEPTION;

StackEmpty : EXCEPTION;

PROCEDURE makeEmpty (someStack : IN OUT aStack;

PROCEDURE push (someStack :IN OUT aStack;

someValue : IN Element);

PROCEDURE pop (someStack : IN OUT aStack;

someValue : OUT Element);

FUNCTION isFull (someStack : IN aStack) RETURN boolean;

FUNCTION isEmpty (someStack : IN aStack) RETURN boolean;

PROCEDURE peek (someStack : IN aStack;

someValue : OUT Element);

PRIVATE

TYPE List IS ARRAY (Positive RANGE <> ) OF Element;

TYPE aStack (Capacity : Positive)IS RECORD

Stuff : List (1..Capacity);

Top : integer := 0;

END RECORD;

END Stacks_Generic;

HOMEWORK:

1. bring your books to class

2. start studying for the test.

a. I suggest you review all the notes

b. Go through the index of the text and highlight the things we have talked about and look at the pages on which they are discussed

3. review your stack programs and make sure that everything you submitted worked and that the specification corresponds to what is above in box #1. IF it did not, you should fix whatever isn’t working and wait for instructions on re-submitting it.

a. specifications

b. implementations

c. test program

4. begin work on your generic stack programs using the guidelines discussed in class. We will discuss what you are having difficulty with at a future class before they are due.