1. CS2301:Computer Programming 2

2. Programming Languages and
Introduction to Computers
Programming Languages and
Algorithms

3. OBJECTIVES
In this Chapter we will learn: 1.1 Introduction 1.2 Computers: What is a Computer? 1.3 Computers: Hardware and Software? 1.4 Computer Organization 1.5 Classification of programming languages 1.6 Machine Languages, Assembly Languages and High-Level Languages 1.7 Programming Language, computer program and Computer Programmer 1.8 Program developing life cycle? 1.9 What do we mean by algorithm? 1.10 Examples of algorithms

4. 1.2 Computers: What is a Computer?
Computer Is a device capable of performing computations and making logical decisions. Another definition: (often referred to as hardware) are controlled by software (i.e., the instructions you write to command the computer to perform actions and make decisions).

5. 1.3 Computers: Hardware and Software (cont.)
Set of instructions that tells the computer to perform specific tasks.
Computers process data under the control of sets of instructions called computer programs.
These programs guide the computer through orderly sets of actions specified by people called computer programmers.
Software may be divided into:
Operating systems e.g. (Windows 7)
Application programs e.g. (Microsoft word)

6. 1.3 Computers: Hardware and Software?
Computer hardware is the collection of physical elements that constitutes a computer system and assist to the input, process, storage, output ….
Various devices comprising computer
Keyboard, screen, mouse, disks, memory, CD-ROM, processing units, etc.

7. 1.4 Computer Organization
Five logical units of computer system
Input unit (Mouse, keyboard)
Output unit (Printer, monitor, audio speakers)
Memory unit (Retains input and processed information)
Central processing unit (CPU) which consists of:
Control unit (Supervises operation of other devices)
Arithmetic and logic unit (ALU):Performs arithmetic calculations and logic decisions.
Secondary storage unit (Hard drives, floppy drives)

8. 1.4 Computer Organization (Cont.) Hardware Components

9. 1.4 Computer Organization (Cont.) Hardware Components

10. 1.4 Computer Organization (Cont.) Hardware Components in Actions
Execution of an Instruction

11. 1.5 The Internet and the World Wide Web
A collection of interconnected networks, all freely exchanging information. Or Global network of computers.
Internet has become one of the world’s premier communication mechanisms.
World Wide Web
Also called the Web, WWW, or W3
Organizes Internet resources throughout the world into a series of menu pages, or screens, that appear on your computer.

12. 1.6 Classification of programming languages

13. 1.7 Programming Languages
Three types of computer languages
1- Machine language
Language of Computer.
Only language computer directly understands
“Natural language” of computer
Defined by hardware design
Binary digit (bit):
The digit 0 or 1
Binary code:
A sequence of 0s and 1s
Byte:
A sequence of eight bits.

14. 1.7 Programming Languages(cont)
Early computers were programmed in machine language.
To calculate wages= rates * hours in machine language
//load
// multiply
// store

15. 1.7 Programming Languages(cont)
2- Assembly language
English-like abbreviations representing elementary computer operations.
Clearer to humans
Incomprehensible to computers
Example
load basepay add overpay store grosspay
Assembler: Translates a program written in assembly language in to machine language.

16. Example of instructions in Assembly Language and Machine Language
1.7 Programming Languages(cont)
Example of instructions in Assembly Language and Machine Language
Machine language
Assembly Language
100100
LOAD
100010
STOR
100110
MULT
100101
ADD
100011
SUB

17. 1.7 Programming Languages(cont)
3- High-level languages
Include Basic, FORTRAN, COBOL, Pascal, C, C++, C# and Java
Similar to everyday English
Uses common mathematical notations
The equation: wages = rate* hours can be written in java as:
Wages = rate * hours;
Another Example:
grossPay = basePay + overTimePay
Compiler: translates a program written in a high-level language in to machine language.

18. 1.8 Programming Language, Computer Program, and Computer Programmer
Is a process of problem solving by using a programming language.
Programming Language:
A set of rules, symbols and special words used to write computer program.
Computer program:
 is a list of instructions, written to perform a specified task on a computer
Syntax:
Rules that specify which statements (instructions) are legal.
Algorithm
- Step–by–step problem solving processes using informal language.

19. 1.8 Programming Language, Computer Program, and Computer Programmer
Examples of Programming Languages:
Fortran
COBOL
Pascal
Ada
Basic C
C++
Objective-C
Visual Basic
Visual C#
PHP
Python
JavaScript
Java

20. Computer Programmer
A programmer, computer programmer, developer, coder, or software engineer: is a person who design, writes and maintains computer software.

21. 1.9 What is program developing life cycle?

22. 1.9 What is program developing life cycle?
step1: Analyze the problem.
- Outline the problem and its requirements.
- Design steps (algorithm) to solve the problem.
Step 2: Implement the algorithm(coding).
- Implement the algorithm code.
- Verify that the algorithm works.
Step 3: Maintenance (when errors occurs)
- Use and Modify the program if the problem domain changes.

23. How Problem Analysis could be done
Understand the overall problem.
Understand problem requirements.
- Does program require user interaction?
Example: When you calculate the area of ​​a rectangle What do we require
from the user? Enter the length of the rectangle, width of the rectangle
- Does program manipulate data?
Example: Equation calculating the area of ​​a rectangle
Area= length * Width
- What is output?
Note
If the problem is complex, divide into sub problems.
Analyze each sub problem as above.

24. 1.9.1 Defining the Problem Keyboard Screen Processing input data
The problem must be defined in terms of:
Input: raw data to be processed.
Output: production of useful information.
processing: converting or transforming data into useful outputs.
Keyboard
Screen
Processing
input data
output data

25. 1.9.2 Input and Output Inputs Outputs
Can come from many sources, such as users, files, and other programs
Can take on many forms, such as text, numbers, graphics, and sound
Outputs
Can also take on many forms, such as numbers, text, graphics, sounds, or commands to other programs

26. 1.9.3 The Problem Analysis-Coding-Execution Cycle
Stages of programming

27. 1.9.3 The Problem Analysis-Coding-Execution Cycle

28. Typical Java development environment.

29. representing algorithms
The Algorithm
Methods for
representing algorithms
Pseudo code
Flow Chart
Note:
Before use any two methods, you must specify the input, processing, and output

30. 1.10.2 The Algorithm- Pseudo Code
An informal language similar to English
Is not considered programming language.
Helps programmers develop algorithms
Does not run on computers
Should contain input, output and calculation actions
Can be easily converted for different programming languages ​​such as Pascal, Java, C++.

31. Example 1: Calculate Area = length*width
Using pseudo code ,write suitable algorithm that calculate the area and perimeter of rectangle and print them.
Area=length * width
Perimeter=2(length * width)
Prompt the user
Input Length and width
Calculate Area = length*width
Calculate Perimeter = 2*( length + width)
Output Area
Output Perimeter
End

32. Calculate Average = Sum/5
Example 2: Using pseudo code write suitable algorithm that calculate and output Sum and Average of 5 numbers
Input five number x1, x2, x3, x4, x5
Calculate Sum = x1+x2+x3+x4+x5
Calculate Average = Sum/5
Output Sum
Output Average
end

33. Using pseudo code ,write suitable algorithm:
Example 3:
Using pseudo code ,write suitable algorithm:
If the student's degree is greater than or equal 60, print “pass” else print “fail”.
Input grade
Check if (grade > 60) then Print "passed"
Else Print "failed“
End

34. Example4: Using Pseudo code, Write suitable algorithm:
Calculate and print the average of temperature degrees for the following readings T1, T2, T3.
Answer:
Input T1, T2, T3
Calculate avg= (T1 + T2 + T3)/3
Output avg
End

35. 1.10.3 The Algorithm-Flow chart
Is a graphical way that explain the steps to solve problem and how they relate to each other
(it is a symbolic representation of the algorithm).

36. Flow chart Start or Stop Program Input or Output
Process, Calculate, Storage
Used to express logical operations or operations report
(Condition)
Arrows determine the direction of the program's progress
Connection

37. Condition Branching No
yes
Compare

38. Condition Rotation

39. start Input : stop Sum = T1+T2+T3 Avg = sum/3 Example 5: claculation:
Using flow chart, Write suitable algorithm:
Calculate and print the average of temperature degrees for the following readings T1, T2, T3.
start
Input
T1, T2, T3
Input :
T1, T2, T3
claculation:
Sum = T1+T2+T3
Avg = sum/3
Output:
Print Avg
Sum = T1+T2+T3
Avg = sum/3
Print avg
stop

40. Example 6:
Using pseudo code and flow chart to write suitable algorithm:
Calculate the average for temperature for the following readings T1, T2, T3.
IF the average is greater than 15 print the average, else print the weather is cold.
start
input
T1, T2, T3
Sum= T1+T2+T3
Start
Input : T1,T2,T3
Process and output
Sum = T1+T2+T3
Avg = sum/3
If avg > 15 then
Print avg
Else
Print “cold”
End if
end
Avg = sum/3 No
Yes
avg > 15
Print “cold”
Print avg
Stop

41. Flow chart Example7: End
Using flow chart to write an algorithm. Enter number (X) and find the value (F), as shown in the following equations:
F= { x x >=0
x x< 0
start
Input x
Yes No
X <= 0
F = x-1
F= x+1
Print F , x
End

42. Note: (if X=0 enter value of X again) Pseudo code input: X process:
Example 8:
Using pseudo code and flow chart to write an algorithm. Enter number (X) and then find and print the value (Y), as shown in the following equation:
Y=(X-2)/X
Note: (if X=0 enter value of X again)
Pseudo code
input: X
process:
if x=0 Re-enter the new value of x
because you can not divide by 0
output: Y
Flow Chart
start
Input X
If X=0
yes No
Y=(X-2)/X
Print Y
stop

43. Discuss Using pseudo code and flow chart to write an algorithm that :
Accept 3 readings of temperature degrees and find the average then check the average
if avg less than 15 : print the “cool air”
if avg between 15 and 25: Print “moderate air”
And if the avg is not verify the previous conditions: print “hot air”

44. Home Work (1)
Using pseudo code and flow chart to write an algorithm that calculate the area of ​​a rectangle print it. Note: area of ​​the rectangle = length × width.
Using pseudo code and flow chart to write an algorithm that find the area of ​​a circle which its radius (R) and print it. Note: The area of ​​a circle is equal to π * R2, where π is a constant value of approximately 3.14.
Using the methods (pseudo code and flow chart), we need to find and print the vicinity of the football stadium, and determine
whether if vicinity is greater than or equal to 600 m then print (international stadium) , and if vicinity is less than 600 then print (local stadium ),
Note: The perimeter of the rectangle is equal to (length + width)×2 .

45. End