Lecture 24 - November 15, 2007

Today we turned in the reverse list recursive function that was due.

We had a LISP quiz based on the homework and on the Lecture 23 notes.

Then we talked about Chapter 6 - as we looked at the slides

We need to remember that a data type and an abstract data type (ADT) consists of a set of values and the operations that can be performed on those values. If she gives us a primitive data type, we should be able to give a typical value and a typical operation. If she gives us an abstract data type (like a queue, a linked list, or a stack) we should be able to tell what operations can be performed.

As we discussed the slides we reviewed that

• integers are stored in the computer in two's complement form;
• two's complement form is preferred to one's complement form because
• there's only one representation of 0
• we don't have to perform an end-around carry
• one's complement and two's complement are preferred to sign magnitude because
• the operations of addition and subtraction are performed using the same algorithm.

We need to know how to convert a positive binary number in twos complement notation to its complement (a negative binary number) and how to convert a negative binary number in two's complement notation to its complement (a positive binary number).

We need to be able to tell what the decimal value of a number in two's complement form is.

We developed the formula to determine the address of a one-dimensional array element as:

base address + (index of desired element - index of first element) * size of element

We need to read chapter 6 and develop the formulas for computing the address of an element stored in a two-dimensional array. It will be on the final!

We learned that most programming languages store their two-dimensional arrays in row major order but FORTRAN stores its two-dimensional arrays in column major order.

We will start Prolog on Tuesday - You can download an interpreter pdprolog.exe from https://users.cs.jmu.edu/adamses/public

Our project 3 submissions will be due next Tuesday.

We will have one more LISP program

We may have one more Snobol program

We will have a Prolog program