1. DDC 1023 – Programming Technique
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DDC 1023 – Programming Technique
Main Reference
Hanly and Koffman, Problem Solving and Program Design in C, Fifth Edition, Addison Wesley
Reference
Joyce Farrell Thomson, Programming Logic and Design, Fifth Edition
DDC1023 PROGRAMMING METHODOLOGY

2. Chapter 1: Overview of Computers and Programming
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Chapter 1: Overview of Computers and Programming
Objectives
Understand computer components and operations
Learn about the steps involved in the programming process
Learn about the data hierarchy and file input
Use flowchart symbols and pseudocode statements
Use and name variables
Use a sentinel, or dummy value, to end a program
Manage large flowcharts
Assign values to variables
Recognize the proper format of assignment statements
Describe data types
Understand the evolution of programming techniques
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3. Chapter 1: Computer Components and Operations
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Chapter 1: Computer Components and Operations
2 major components of computer system:
Hardware
Software
Hardware: equipment, or devices
Software: programs that contain instructions for the computer
4 major operations in a computer:
Input
Processing
Output
Storage
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4. Chapter 1: Computer Components and Operations
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Chapter 1: Computer Components and Operations
Input devices: allow data to enter the computer
Mouse, keyboard, scanner
Processing: working on the data
Organizing data
Checking data for accuracy
Mathematical or other manipulations on data
Central Processing Unit (CPU): hardware that performs the tasks
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5. Chapter 1: Computer Components and Operations
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Chapter 1: Computer Components and Operations
Output devices: provide data to the user
Printer, monitor, speakers
Programming language: special language containing instructions for the computer
Visual Basic, Java, C#, C++, COBOL
Syntax: rules governing word usage and punctuation in the language
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6. Chapter 1: Computer Components and Operations
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Chapter 1: Computer Components and Operations
Machine language: controls the computer’s on/off circuitry
Compiler or interpreter: software that translates programming languages to machine language
Program must be free of syntax errors to be run, or executed, on a computer
To function properly, the logic must be correct
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7. Chapter 1: Computer Components and Operations
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Chapter 1: Computer Components and Operations
What is wrong with this logic for making a cake?
Stir
Add two eggs
Bake at 350 degrees for 45 minutes
Add three cups of flour
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8. Chapter 1: Computer Components and Operations
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Chapter 1: Computer Components and Operations
Logic errors, or semantic errors, are more difficult to locate than syntax errors
Logic for multiplying a number by 2 (includes input, processing, and output statements)
Get input number.
Compute calculated answer as
inputNumber times 2.
Print calculatedAnswer.
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9. Chapter 1: Computer Components and Operations
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Chapter 1: Computer Components and Operations
2 storage categories:
internal
external
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10. Chapter 1: Computer Components and Operations
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Chapter 1: Computer Components and Operations
Internal storage:
Main memory, random access memory (RAM)
Located inside the computer system
Volatile: contents are lost when power goes down
External storage:
Persistent: contents are relatively permanent
Floppy drive, hard drive, flash media, magnetic tape
Located outside the computer system
Non-volatile: contents remain eventhough power goes down
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11. Chapter 1: Steps Involved in the Programming Process
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Chapter 1: Steps Involved in the Programming Process
6 programming phases:
Understand the problem
Plan the logic
Code the program
Use software to translate the program to machine language
Test the program
Put the program into production
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12. Chapter 1: Steps Involved in the Programming Process
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Chapter 1: Steps Involved in the Programming Process
Understanding the Problem
May be the most difficult phase
Users may not be able to articulate their needs well
User needs may be changing frequently
Programmers may have to learn the user’s functional job tasks
Failure to understand the problem is the major cause of most project failures
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13. Chapter 1: Steps Involved in the Programming Process
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Chapter 1: Steps Involved in the Programming Process
Planning the Logic
Plan the steps that the program will take
Use tools such as flowcharts and pseudocode
Flowchart: a pictorial representation of the logic steps
Pseudocode: Natural language representation of the logic
Walk through the logic before coding by desk-checking the logic
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14. Chapter 1: Steps Involved in the Programming Process
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Chapter 1: Steps Involved in the Programming Process
Coding the Program
Select the programming language
Some languages more efficient for certain tasks
All languages handle input, arithmetic processing, output, other standard functions
Logic can be executed in any number of languages
Write the instructions
Planning generally more difficult than coding
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15. Chapter 1: Steps Involved in the Programming Process
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Chapter 1: Steps Involved in the Programming Process
Using Software to Translate the Program into Machine Language
Programmers write instructions in high-level languages that resemble a natural language
Compilers or interpreters change the programs into a low-level machine language that can be executed
Syntax errors are identified by the compiler or interpreter
DDC1023 PROGRAMMING METHODOLOGY

16. Chapter 1: Steps Involved in the Programming Process
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Chapter 1: Steps Involved in the Programming Process
Using Software to Translate the Program into Machine Language
Creating an executable program
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17. Chapter 1: Steps Involved in the Programming Process
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Chapter 1: Steps Involved in the Programming Process
Testing the Program
Execute it with sample data and check results
Identify logic errors and correct them
Choose test data carefully to exercise all branches of the logic
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18. Chapter 1: Steps Involved in the Programming Process
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Chapter 1: Steps Involved in the Programming Process
Putting the Program into Production
Might mean simply running the program once
Process might take months if program is used on regular basis or is part of larger development
Train data-entry people and users
Change existing data
Conversion: entire set of actions organization must take to switch over to new program(s)
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19. Chapter 1: Steps Involved in the Programming Process
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Chapter 1: Steps Involved in the Programming Process
Software Development Method
1 Planning
2 Analysis
Identify data objects
Goal to model properties
Determine Input / Output data
Constraints on the problem
3 Design
Decompose into smaller problems
Top-down design (divide and conquer)
Develop algorithm (Desk check)
4 Implementation
Writing the algorithm
5 Testing
Verify the program meets requirements
System and Unit test
6 Maintaining
Maintain the system
DDC1023 PROGRAMMING METHODOLOGY

20. Chapter 1: Interactive Input
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Chapter 1: Interactive Input
Prompt: message displayed on a monitor
Asks the user for a response
Command prompt: location to type entries to communicate with the operating system
Graphical User Interface (GUI): allows users to interact with a program in a graphical environment
DDC1023 PROGRAMMING METHODOLOGY

21. Chapter 1: Interactive Input
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Chapter 1: Interactive Input
A prompt, response, and output in a command line environment
DDC1023 PROGRAMMING METHODOLOGY

22. Chapter 1: Interactive Input
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Chapter 1: Interactive Input
A prompt, response, and output in a GUI environment
DDC1023 PROGRAMMING METHODOLOGY

23. Chapter 1: Flowchart Symbols and Pseudocode Statements
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Chapter 1: Flowchart Symbols and Pseudocode Statements
Input symbol
Processing symbol
Output symbol
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24. Chapter 1: Flowchart Symbols and Pseudocode Statements
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Chapter 1: Flowchart Symbols and Pseudocode Statements
Flowlines:
Connect the steps
Show the sequence of statements
Have arrows to show the direction
Terminal symbol (start/stop symbol):
Shows the start and end points of the statements
Lozenge shape
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25. Chapter 1: Flowchart Symbols and Pseudocode Statements
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Chapter 1: Flowchart Symbols and Pseudocode Statements
Flowchart and pseudocode of program that doubles a number
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26. Chapter 1: Flowchart Symbols and Pseudocode Statements
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Chapter 1: Flowchart Symbols and Pseudocode Statements
Inefficient pseudocode for program that doubles 10,000 numbers
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27. Chapter 1: Flowchart Symbols and Pseudocode Statements
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Chapter 1: Flowchart Symbols and Pseudocode Statements
Flowchart of infinite number-doubling program
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28. DDC1023 PROGRAMMING METHODOLOGY
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Chapter 1: Summary
4 major computer operations:
Input
Processing
Output
Storage
6 programming phases:
Understand the problem
Plan the logic
Code the program
Translate the program to machine language
Test the program
Deploy the program
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29. DDC1023 PROGRAMMING METHODOLOGY
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Chapter 1: Summary
Software Development Method
Planning
Analysis
Design
Implementation
Testing
Maintaining
DDC1023 PROGRAMMING METHODOLOGY