What we’ll Learn: Defining and calling a module Passing arguments to module Hierarchy chart Pseudocode Flow chart

1. CSWD1001
Programming Methods
Modules
18/9/2018
CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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2. What we’ll Learn
• Defining and calling a module
• Passing arguments to module
• Hierarchy chart
• Pseudocode
• Flow chart
18/9/2018
CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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3. What is Module
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(FCUC)
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4. A module
is a
group of statements that exist within a
program for the purpose of performing
a specific task
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CSWD1001 @ Kwan Lee First City Unversity Malaysia
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5. Benefits
using
Module
Simpler code
Code reuse
Better testing
Easier maintenance
Faster development
Easier facilitation of teamwork
18/9/2018
CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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6. How to Define Module
Module name()
statement
statement
etc
End Module
A header (starting point)
A body
End point
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CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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7. Example
Module main()
Display "I have a message for you."
Call showMessage()
Display "That's all, folks!"
End Module
To execute a module,
you call it
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CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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8. Another example
Module main()
Display "I have a message for you."
Call showMessage()
Display "That's all, folks!"
End Module
Module showMessage()
Display "Hello world"
End Module
The program begins executing at
the main module.
When the end of the main module
is reached, the program stops
executing.
The computer jumps to
the showMessage module and executes
the statements in its body.
18/9/2018
CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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9. Local vs Global Variables
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10. Local Variable
Declared inside a module
Cannot be accessed by statements that are outside the module
Different modules can have local variables with the same
names
18/9/2018
CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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11. Example Local Variable
Module main()
Call getName()
Display "Hello"
End Module
Module getName()
Declare String name
Display "Enter your name"
Input name
End Module
Local variable
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CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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12. Global Variables
Is accessible to all the module
Declaration statement is outside of all module
18/9/2018
CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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13. Example Global Variable
Declare Integer number
Module main()
Display "Enter a number."
Input number
Call showNumber()
End Module
Module showNumber()
Display "The number you entered is ", number
End Module
Global variable
18/9/2018
CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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14. Passing Arguments to Modules
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15. • An argument is any piece of data that is passed into a module when
the module is called
• If you want a module to receive arguments when it is
called, you must equip the module with one or more
parameter variables.
• A parameter is a variable that receives an argument that is
passed into a module.
18/9/2018
CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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16. Simple Example
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17. Two Type of Passing Arguments
Value
• Only a copy of the argument’s
value is passed into the
parameter variable
• If the contents of the parameter
variable are changed inside the
module, it has no effect on the
argument in the calling part of
the program
Reference
• The argument is passed into a
special type of parameter known
as a reference variable.
• When a reference variable is
used as a parameter in a module,
it allows the module to modify
the argument in the calling part
of the program
18/9/2018
CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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18. Example Passing
Arguments by Value
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19. Example Passing Arguments by References
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20. Passing multiple arguments
• Most languages allow you to write modules that accept multiple
arguments.
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21. Rules to Remember
when
Passing an Arguments
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22. Argument and the receiving parameter variable be
of the same data type
If you try to pass different type, an error usually
occurs
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CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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24. 18/9/2018
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25. Hierarchy Charts
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26. Hierarchy Charts
show the
relationship between the modules
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27. Flow of Hierarchy Charts
Main
Program
Module 1 Module 2 Module 3
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28. Example Main Program
receiveOrder()
Confirm()
printCustomerData()
checkAvailability()
processOrder() billCustomer()
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CSWD1001 @ Kwan Lee First City Unversity Malaysia
(FCUC)
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29. Flow Chart of Modules
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30. Symbol
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31. Flowchart Notation Meaning
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32. Terminal / Terminator
• Marks the starting or
ending point of the
system
• Usually contains the
word “Start” or “End”
Action/Process
• Represent a single step
or and entire sub-
process within a larger
process
Document
• Printed document or
report
Data/Input/Output
• Information entering as
input
• Information display as
output
Decision
• System decision
Database
• Storage information
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33. 18/9/2018
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34. Summary
• Programmers break down programming problems into reasonable units called modules,
subroutines, procedures, functions, or methods.
• To execute a module, you call it from another program or module
• When you create a module, you include a header, a body, and a return statement.
• When a main program wants to use a module, it “calls” the module’s name
• Th e variables and constants declared in a module are usable only within the module; they
are local to the module. Global variables and constants are those that are known to the
entire program.
• You can use a hierarchy chart to illustrate modules’ relationships. A hierarchy chart tells
you which modules exist within a program and which modules call others.
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35. End
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