CMPT 115 Lecture Notes - Lecture 1: Computer, Goback, Abbreviation
Course CodeCMPT 115
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CMPT 115 lecture notes
Notes written by Michael Horsch, Mark Eramian, Ian McQuillan, Lingling Jin, and Dmytro Dyachuk
By the end of this lecture topic, you are expected to be able to:
1. Describe the process of abstraction
2. Give examples of abstraction
3. Describe the process of top-down design (stepwise reﬁnement)
4. Give examples of top-down design (stepwise reﬁnement)
5. Deﬁne the terms C. E. R. A. R.
6. Describe the beneﬁts of data organization.
1 Levels of Abstraction 1
2 Top-Down Design 3
3 Application Design 4
4 Storing and Manipulating Data 6
1 Levels of Abstraction
Abstraction is the process of extracting or distilling the underlying essence or important properties of a
concept, removing some or all dependence on real world objects with which it might originally have been
•Information is represented electronically in a computer by voltages, at diﬀerent levels.
•If the voltage is “high”, a computer interprets this as a “1”. If the voltage is “low”, then a computer
interprets this as a “0”.
•However, voltage is measured on a continuous scale, not just in two distinct states.
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Abstraction: voltages ⇒states
Levels of abstraction
Purpose or main point only
with some details included
Purpose fully realized
with all details included
Sort student numbers
Input: an int array
Output: sorted array
void sort(int a, int size)
// code omitted for brevity
Building abstraction hierarchies
•When we have some abstraction, we can build another abstraction on it.
•The new abstraction is at a higher level of abstraction.
•Example: natural sciences
A Hierarchy of scientiﬁc abstraction ??
physics, chemistry, biology
Computer system - levels of abstraction
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