1. Module 10 Programming ___tell computers what to do
Problem solving with computers
Problem → Solution → Algorithm → Programming → Execution
Problems: mean, median, mode, max, min, search
Generations of programming languages
Machine, assembly high level, very high level, natural
Examples of program languages
Programming techniques
procedure oriented programming
object-oriented programming
Programming examples

2. Programming
Program – a set of detailed, step-by-step instructions that directs the computer to do what you want it to do
Programming language – a set of rules that provides a way of telling the computer what operations to perform

3. Problem Solving with Programming
Main steps
Defining the problem
Planning the solution
Designing an algorithm
Coding the program
Testing and executing the program
Maintaining and documenting the program

4. Defining the Problem Develop a written agreement that specifies:
The input data
The desired output
Example: Input: a list of numbers Output: the mean of the numbers

5. Planning the Solution Find out a solution to the problem
Algorithm – a detailed, step-by-step solution to the problem
Flow chart or pseudo code can be used as a tool
Check the solution
Carry out each step of the algorithm with pencil and paper
Example: Given a[1], a[2], ……, a[100]
n = 100 s ← 0, s ← s+a[1], s ← s+a[2], …, s ← s+a[100]
mean = s/n;

6. Planning Tools Flowchart – a pictorial representation of the algorithm
Start
read a[i] i=1, …, 100
s = 0 i =1
s = s +a[i]
i = 100?
Stop
s / i
Yes No
i = i +1
Flowchart – a pictorial representation of the algorithm
Pseudo code – English-like language
e.g. Input: a[i], i = 1, …, 100 s ← 0 for i from 1 to 100 do s ← s + a[i] output: s / n

7. Algorithm Implementation / Program Coding
Translating the algorithm from the planning stage into a program in a formal programming language
All languages have syntax rules (grammar)
Similar to grammatical rules
The computer will reject a program with even a minor syntax error
Programs can be keyed into the computer by using a text editor
See examples: calculate … + 100

8. Testing the Program Two phases of testing the program Translation
Converting the program you wrote into the binary instructions the CPU understands
Debugging
Identifying and correcting logic errors in the program

9. Translation / execution
Compiler translates the program (source module) into a machine language version (object module)
If the compiler detects syntax errors, it will produce messages describing those errors
If no syntax errors exist, the object module will be linked to create a load module
Load module is executed by the computer
Run the program to get the output

11. Maintaining and Documenting
Update the program to meet new requirement
Record materials are generated at each part of the process
Common examples of documentation
Flowchart and/or pseudocode
Comments within the source code
Testing procedures
Layouts of input and output records
A narrative description of the program

12. Levels of Languages
Lower-level languages – more like the 0s and 1s the computer itself uses
Higher-level languages – more like the languages people use
Divided into five generations

13. Five Generations of Languages
Machine language
Assembly languages
High-level languages
Very high-level languages
Natural languages

14. Machine Language
Programs and memory locations are written in strings of 0s and 1s
Add the numbers in registers s1 and s2 and put the result in t0
Problems with machine languages
Programs are difficult to write and debug
Each computer has its own machine language
Only option available to early programmers

15. Assembly Languages Substitute mnemonic codes for 0s and 1s
For example => add $t0, $s1, $s2.
Use names rather than binary addresses for memory locations
Require an assembler to translate the program into machine language
Still used for programming chips and writing utility programs

16. High-Level Languages (HLL)
Transformed programming
Programmers could focus on solving problems rather than manipulating hardware
Programs could be written and debugged much more quickly
Requires a compiler to convert the statements into assembly /machine language
Each computer has its own version of a compiler for each language

17. Very High-Level Languages
Also called fourth-generation languages (4GLs)
Considered nonprocedural languages
The programmer specifies the desired results, and the language develops the solution
Programmers can be about 10 times more productive using a fourth-generation language than a third-generation language

18. Natural Languages Resemble written or spoken English
Programs can be written in a natural syntax, rather than in the syntax rules of a programming language
The language translates the instructions into code the computer can execute

19. Examples of High Level Programming Languages
FORTRAN
COBOL
BASIC C
Java

20. FORTRAN The first high-level language Stands for FORmula TRANslator
Used primarily for engineering, mathematical, and scientific tasks
Good for numerical computation

21. COBOL Stands for COmmon Business-Oriented Language
Used primarily for business requirements
Processes large data files
Produces well-formatted reports

22. BASIC Stands for Beginners’ All-Purpose Symbolic Instruction Code
Developed to teach programming to college students
Became very popular with the introduction of the microcomputer

23. C Originally designed to write systems software
Offers the ease of use of a high-level language with the efficiency of an assembly language
Very portable – can be used with virtually every combination of computer and operating system

24. Java
A network-friendly programming language that permits a piece of software to run directly on many different platforms
Allows programmers to write one version of the program, rather than a separate version of each platform
Very useful for Internet development
Java applets can run in the user’s Web browser

25. Algorithm Designs The algorithm must be correct.
Can stop in reasonable amount time
Give the correction answer / solution
Robust
The algorithm should be efficient
Use less amount of time to complete the computation
Use less amount of memory space to carry out the compute

26. Program Design Structured Programming
Get input:
from keyboard, file, generate automatically
Computation on the input by the algorithm
the core of the program implementing an algorithm
Output the result
to screen, file, in certain format

27. Procedure Oriented Programming
Features: linear style, the program has a main stream
Fortran, basic, C are languages for POP
Common features
Data type and variable: integer, floating point, list, etc
Modular: routine, procedure, function and library
Programming constructs:
serial, selection/branch, repetition/loop

28. Program constructs There are basic three programming constructs
Sequential
do things one by one in sequence
Selection:
do one thing under a condition; do another thing under another condition
If statement
Repetition:
do the same thing for many times
For loop
A program consists of a combination of the three construct

29. Sequential construct Selection construct
<script type = "text/javascript">
<!--
var a = prompt("What is the value of 'a'? \n", "");
var b = prompt("What is the value of 'b'? \n", "");
var c = prompt("What is the value of 'c'? \n", "");
var denom = 2.0 * a;
var det = b * b * a * c;
if (det >= 0){
var root_part = Math.sqrt(det);
var root1 = (-b + root_part) / denom;
var root2 = (-b - root_part) / denom;
document.write("The first root is: ", root1, "<br />");
document.write("The second root is: ", root2, "<br />"); }
else {
var root_part = Math.sqrt(-det);
var real = -b / denom;
var imagine = root_part / denom;
document.write("The first root is: ", real,"+", imagine, "i", "<br />");
document.write("The second root is: ", real, "-", imagine,"i", "<br />");
-->
</script>
Sequential construct
Selection construct

30. <script type = "text/javascript">
<!--
// Get input n
var n = prompt("What is the value of 'n'? \n", "");
var sum =0;
var i;
// compute the sum
for (i = 1; i<= n; i++)
sum = sum + i;
// display the result
document.write("The sum of ", n, " = ", sum, "<br />");
-->
</script>
Repetition construct

31. Four programming examples
Calculate the mean of a given data set
Find the max or min of a given data set
Sort the given data set in increasing order
Calculate the median
Question :
How do you find the mode of a given data set ?

32. Mean Input: a[0], …, a[n-1] Output: (a[0]+…+a[n-1])/n
Pseudo code sum = 0 for i from 0 to n-1 do sum ¬ sum + a[i] end for mean = sum/n output mean

33. <script type = "text/javascript">
<!--
// Input: data set
var data_set = new Array(1, 6, 4, 6, 3, 10);
// computation
n = data_set.length;
sum = 0;
for (i = 0; i<n; i++){
sum = sum + data_set[i]; }
mean = sum/n;
//output
document.write("<p>The mean of the data set is ", mean, "</p>");
// -->
</script>

34. Find maximum Input: a[0], …, a[n-1]
Output: the maximum of a[0], …., a[n-1]
Pseudo code max = a[0] for i from 1 to n-1 do if a[i] > max then max ¬ a[i] end for output max

35. <script type = "text/javascript">
<!--
// Input: data set
var data_set = new Array(33, 61, 71, 10, 23, 29, 99);
// computation
length = data_set.length;
var current_max = data_set[0];
for (i = 1; i<length; i++){
if (data_set[i] > current_max)
current_max = data_set[i]; }
//output
document.write("<p>The maxium element is: ", current_max, "</p>");
// -->
</script>

36. Sort (in increasing order)
Input: a[0], …, a[n-1]
Output: a list of a[0], …., a[n-1] in increasing order
Pseudo code for i from 0 to n-1 do find a[j] minium amount a[i], … a[n-1] if j is not equal to I swap a[i] and a[j] end for output a[0]

37. <script type = "text/javascript">
<!-- // Input: data set
data_set = new Array(10, 6, 4, 6, 3, 1, -2);
// sortting
n = data_set.length;
for (i = 0; i<n; i++){
min = data_set[i];
min_position = i;
for (j = i; j<n; j++){
if (data_set[j] < min){
min = data_set[j];
min_position = j; }
if (min_position != i) {
data_set[min_position] = data_set[i];
data_set[i] = min;
//output
for (i=0; i<n; i++)
document.write(data_set[i], ", ");
//-->
</script>

38. Median Input: a[0], …, a[n-1] Output: the median of a[0], …., a[n-1]
Pseudo code sort a[0], …., a[n-1] if n is odd ouput a[(n+1)/2] else output (a[n/2-1]+a[n/2])/2

39. data_set = new Array(10, 6, 4, 6, 3, 1);
n = data_set.length;
for (i = 0; i<n; i++){
min = data_set[i];
min_position = i;
for (var j = i; j<n; j++){
if (data_set[j] < min){
min = data_set[j];
min_position = j; }
if (min_position != i) {
data_set[min_position] = data_set[i];
data_set[i] = min;
if (n % 2 == 0)
median = (data_set[n/2-1]+data_set[n/2])/2;
else
median = data_set[(n-1)/2];
document.write("The median is ", median);

40. Object-Oriented Programming
Object – a self-contained unit that contains both data and its related functions
Key terms in object-oriented programming
Encapsulation – an object isolates both its data and its related instructions
Attributes – facts that describe the object
Also called properties
Methods – instructions that tell the object to do something
Messages – an outside stimulus that results in the change of the state of an object

41. Using Objects Programmers define classes of objects
The class contains all attributes that are unique to objects of that class
An object is an instance (occurrence) of a class
Objects are arranged hierarchically in classes and subclasses
Subclasses are derived from classes
Inheritance – a subclass possesses all attributes of the class from which it is derived
Additional attributes can be coded in the subclasses

42. Activating the Object
A message is sent to the object, telling it to do something
The object’s methods tell it how to do it
Polymorphism – each object has its own way to process the message
For example, the class may have a Move method, but each subclass implements that method differently

43. Object-Oriented Languages
Java C#
Visual Basic

44. C++ An enhancement of the C language
Includes all features of C
Adds support for object-oriented programming
Can be used as simply an improvement of C, without the object-oriented features

45. Java A pure object-oriented program
Used to create small programs called applets
Applets can be delivered over the Web and run on any platform

46. C# Microsoft’s answer to Java
Has the same advantages over C++ that Java has
Designed to work within Microsoft’s .NET environment
.NET is designed for building, deploying, and running Web-based applications

47. Visual Basic Allows programmer to create Windows-like user interfaces
Programmer drags a control (button, text box, etc.) onto the form
VB creates the code associated with that control
VB is event-driven
The user controls the program
Previous versions supported some object technology
The current version, VB.NET, is the first to support inheritance and polymorphism
These two traits are required for a true object-oriented language