The document outlines essential programming methods and design methodologies, including the creation of variables, constants, and arithmetic operations. It emphasizes the importance of understanding user requirements, breaking tasks into steps, and performing declarations and assignments. Additionally, it discusses the need for good planning and design in programming as projects grow in complexity.

1. CSWD1001
Programming Methods
Program Design Methodology – Data, Design
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CSWD1001 @ Kwan Lee First City Unversity Malaysia
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2. What we’ll Learn
• How you design a program
• Declaring and using variables and constants
• Assigning values to variables
• Named constants
• The need for good planning and design
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3. How you design a Program ??
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4. Two steps:
1. Understand the task that the program is to perform.
• User requirements – gains related information through interview a
customer
• Create a list of different software requirements based on the data
gathered
2. Determine the steps that must be taken to perform the task.
• Breaking down the task into a series of steps.
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5. Example Step Designing a Program
• Step 1 Understand the task that the program is to perform.
• Calculate and display the gross pay for an hourly paid employee.
• Step 2 Determine the steps that must be taken to perform the
task.
• Get the number of hours worked.
• Get the hourly pay rate.
• Multiply the number of hours worked by the hourly pay rate.
• Display the result of the calculation that was performed in Step 3.
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6. Example Converting Algorithm to
Pseudocode
Algorithm
• Step 1 Understand the task that the program is to perform.
• Calculate and display the gross pay for an hourly paid
employee.
• Step 2 Determine the steps that must be taken to perform
the task.
• Get the number of hours worked.
• Get the hourly pay rate.
• Multiply the number of hours worked by the hourly pay
rate.
• Display the result of the calculation that was performed in
Step 3.
Pseudocode
Display "Enter the number of hours the employee worked."
Input hours
Display "Enter the employee's hourly pay rate."
Input payRate
Set grossPay = hours * payRate
Display "The employee's gross pay is $", grossPay
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7. Example Converting Pseudocode to
Flowchart
Pseudocode
Display "Enter the number of hours the
employee worked."
Input hours
Display "Enter the employee's hourly pay rate."
Input payRate
Set grossPay = hours * payRate
Display "The employee's gross pay is $",
grossPay
Flowchart
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8. Working with Variables ??
What is Variables ??
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9. Variables is a
storage location in memory
that is
represented by a name
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10. Features of a Variables
•Holds just one value
•Declare before using it (Declaration)
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11. How you do a Declaration
Declare data type [name of the variable]
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12. Example
Declare number myNumber
Declare number myAnswer
Declare number mySalary
Declare string myName = “Kwan Lee”
Declare string courseName = “Programming Method”
Declare number courseCode = 1014
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13. Rules in
Naming
a
Variable
Meaningful
Allow combination: Letter + digit + underscore
Length: unlimited but depend on the languages
First character cannot be a number
Names must be in one words
Cannot contain space
No punctuation character
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14. Example of Rules in Naming a Variable
Do not Do
Register,module
Register module
1registerModule
Do
Registermodule
Registermodule
registerModule
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15. Format of Naming Variables
Camel Casing
• Start with lowercase and
subsequent word begin with an
uppercase letter
• Example
• hourlyWage
• myName
• courseModule
Pascal Casing
• First and subsequent word is
uppercase
• Example
• HourlyWage
• MyName
• CourseModule
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16. Variable Initialization & Un-initialized
Initialization
• Assign a value to the variable
• Example
Declare price = 49.95
Display “ I have”, price, “in my account”
Un-initialized
• Do not assign a value to the
variable
• Example
Declare price
Display “I have “, dollars, “ in my account.”
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17. Be careful with GARBAGE variable
A variable’s unknown value before initialization
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18. Declare a Constant Variable Name
A named constant is similar to a variable,
except it can be assigned a value only once
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19. Example of Declare a Constant Variable
Name
Declare constant number discountPercentage = 0.2
Declare constant float salaryOT = 46.50
Declare constant string nameUniversity = “FCUC”
Assigning values to
variables.
Explanation – you a
assigning values of 2 to
the data type of number
with a variable name of
discountPercentage
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20. Avoid a MAGIC variable
The unnamed constant
Example
If a program uses a sales tax rate of 6%, you might want to declare a named constant
as follows:
num SALES_TAX = 0.06
You then might use SALES_TAX in a program statement similar to the following
set taxAmount = price * SALES_TAX
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21. Understanding the Data Types of Variables
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22. A variable’s data type
is
simply the type of data that the variable will hold
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23. The Types of Data Variable
Categories Types Example
Numeric Digits 1, 2, 3
Decimal 1.1, 2.1, 3.1
Sign (positive/negative) -1, -2, +3
String Text (letters/alphabet) Number, digit
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24. Performing Arithmetic Operations
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25. What is Arithmetic Operation
An arithmetic operator
is a
mathematical function that takes two
operands and performs a calculation on
them.
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26. Four Arithmetic Operators
+ (plus sign) — addition
− (minus sign) — subtraction
* (asterisk) — multiplication
/ (slash) — division
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27. • In programming languages, you can combine
arithmetic statements.
• When you do, every operator follows rules of
precedence (also called the order of operations)
that dictate the order in which operations in the same
statement are carried out
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28. Rules of Precedence for Basic Arithmetic
Statements
• Expressions within parentheses are evaluated first. If there
are multiple sets of parentheses, the expression within the
innermost parentheses is evaluated first.
• Multiplication and division are evaluated next, from left to
right.
• Addition and subtraction are evaluated next, from left to
right.
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30. Exercise
• Assume that cost = 10 and price = 12. What is the value of
each of the following expressions?
•price - cost * 2
•5 + price - 3 * 2
•(price + cost) * 3
•4 - 3 * 2 + cost
•cost * ((price - 8) + 5) + 100
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31. Answer
• 12 – 10 * 2 = 12 -20 = -8
• 5 + 12 – 3 * 2 = 5+12-6 = 17-6 =11
• (12+10) x 3 = 22 x 3 = 66
• 4-3*2 + 10 = (4 – 6) + 10 = -2 + 10 = 8
• 10 *((12-8)+5) + 100 = 10*(4+5) + 100 = 10*9 + 100 = 90 +100 = 190
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32. Arithmetic  Formula  Programming Statements
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34. Exercise
Convert Celsius to Fahrenheit Formula
𝐹 =
9
5
𝐶 + 32
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35. Answer
Formula
𝐹 =
9
5
𝐶 + 32
Programming Statement
Fahrenheit = (Celsius *9)/5) + 32
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36. The need
for
good planning and design
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37. Some practises
• Reason contribute
system getting bigger and bigger
• Some practises
• Using Program Comments
• Use a meaning name for your data types
• Avoiding Confusing Line Breaks
• Using Temporary Variables to Clarify Long Statements
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39. Summary
• Variables are named memory locations, the contents of which can vary.
• Before you can use a variable in any program, you must include a
declaration for it.
• A declaration includes a data type and an identifi er. Every computer
programming language has its own set of rules for naming variables;
however, all variable names must be written as one word without embedded
spaces, and should have appropriate meaning.
• Data types include numeric and string. A named constant is similar to a
variable, except it can be assigned a value only once.
• Most programming languages use +, −, *, and / as the four standard
arithmetic operators.
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40. Summary
• As your programs become larger and more complicated, the need for
good planning and design increases.
• You should use program comments where appropriate. Choose
identifiers wisely, strive to design clear statements within your
programs and modules, write clear prompts and echo input, and
continue to maintain good programming habits as you develop your
programming skills.
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41. END
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