Modules

1
Modules the Basics

• CSCE 110
• Influenced by material developed by James Tam
  Jennifer Welch

2
Where To __________ Modules
Module ________ (___________ ____________)
3
Procedures (Basic Case)
Procedure call
No Information Is Passed In/ No Parameters
4
Defining Procedures (Basic Case No __________)

• Format
• procedure name
• begin
• Statements of the procedure go here
• end End of procedure name
• Example
• procedure displayInstructions
• begin
• writeln ('The statements in this module
  will')
• writeln (' typically give a high level')
• writeln (' overview of what the program as
  a')
• writeln ('whole does')
• end ( End of procedure displayInstructions )

5
Calling A Procedure (Basic Case No __________)

• Format
• name
• Example
• displayInstructions

The name of the procedure is a ____________.
6
Where To ______ Modules

• It can be done ________________________ in the
  program but must be done ___________ its
  ____________.

Header
Declarations
const
Modules can be ______ from the ______________ of
the program or from within any _______ as long as
the __________ is already ___________.
Module definitions
Main Body
begin end.
7
Important A Module Must Be ________ Before It
Can Be ___________!
program exampleModule (output) procedure
exampleProcedure begin end begin
exampleProcedure end.
8
Important A Module Must Be ________ Before It
Can Be ________!
program exampleModule (output) begin
exampleProcedure end. procedure
exampleProcedure begin end
9
Procedures

• firstExampleProcedure.pas
• program firstExampleProcedure (output)
• procedure displayInstructions
• begin
• writeln ('The statements in this module will
  typically give a)
• writeln (high level overview of what the
  program as a)
• writeln (whole does')
• end (Procedure displayInstructions )
• begin
• displayInstructions
• writeln('Thank you, come again!')
• end. ( Program )

10
Procedures

• firstExampleProcedure.pas
• program firstExampleProcedure (output)
• procedure displayInstructions
• begin
• writeln ('The statements in this module will
  typically give a)
• writeln (high level overview of what the
  program as a)
• writeln (whole does')
• end (Procedure displayInstructions )
• begin
• displayInstructions
• writeln('Thank you, come again!')
• end. ( Program )

Procedure ___________
Procedure ___________
11
Declaring _______ Variables

• Format
• procedure name
• var
• ltvariable 1 namegt ltvariable 1 typegt
• ltvariable 2 namegt ltvariable 2 typegt
• 
  
• begin
• end
• Example
• procedure proc
• var
• num1 integer
• num2 integer
• begin
• end

12
Declaring __________ Variables

• program secondExampleProcedure (output)
• procedure proc
• var
• num1 integer
• begin
• var num2 integer
• num1 1
• num2 2
• writeln(num1, ' ', num2)
• end
• begin
• var num1 integer
• num1 10
• writeln(num1)
• proc
• writeln(num1)
• end.

13
Declaring ________ Variables

• secondExampleProcedure.pas
• program secondExampleProcedure (output)
• procedure proc
• var
• num1 integer
• begin
• var num2 integer
• num1 1
• num2 2
• writeln(num1, ' ', num2)
• end
• begin
• var num1 integer
• num1 10
• writeln(num1)
• proc
• writeln(num1)
• end.

______ variable procedure proc
________ variable main module
14
______ Variables Have ____________________

• procedure getInformation
• begin
• write (Enter the principle )
• readln (principle)
• end
• procedure calculateInterest
• var
• amount integer
• principle integer
• interest integer
• time integer
• begin
• getInformation
• end

15
___________________ To Modules

• Modules generally arent useful unless they can
  ______________________.

computeChange
16
Procedures With ____________________ Passed In
Procedure call
P1
P2
Pn
Procedure definition
17
Defining Modules (Procedures) With ____________

• Format
• procedure name (Name of parameter 1 type of
  parameter 1
• Name of parameter
  2 type of parameter 2
• Name of parameter n type of parameter n)
• begin
• ( Statements of the procedure go here
  )
• end
• Example
• procedure celciusToFahrenheit (celciusValue
  real)
• var
• fahrenheitValue real
• begin
• fahrenheitValue 9 / 5 celciusValue
  32
• writeln(temperature in Celsius ',
  celciusValue02)
• writeln(temperature in Fahrenheit ',
  fahrenheitValue02)
• end ( Procedure celciusToFahrenheit )

18
Calling Modules (Procedures) With Parameters

• Format
• name (Name of parameter 1, Name of
  parameter 2Name of parameter n)
• Example
• celciusToFahrenheit (celciusValue)

_________Parameters
19
________ and _________ Parameters

• __________ parameters The parameters in the
  method _______________.
• __________ parameters The parameters in the
  method _______________.
• Parameters act like _________________ within a
  module.

20
____________ and ______________ Parameters

• Module call and module definition must have
• _____________ of parameters
• ______________ parameters must have the same
  _______
• e.g. definitionprocedure calc(i integer, f
  real, bboolean)e.g. call calc(num, avg,
  flag)where
• _____ must be of type ____________
• _____ must be of type ____________
• _____ must be of type ____________

21
Important The _____ and _____ Parameter Lists
Must _____!

• The ______ and _________ of parameters must
  ________ or there will be a compilation error.

program parameterExample procedure proc (num
integer) begin num 10 end begin
var num integer proc (num) end.
22
Important The _____ and _____ Parameter Lists
Must _____!

• The ______ and _________ of parameters must
  ________ or there will be a compilation error.

program parameterExample procedure proc (num
integer) begin num 10 end begin
proc end.
23
Important The _____ and _____ Parameter Lists
Must _____!

• The ______ and _________ of parameters must
  ________ or there will be a compilation error.
• .

program parameterExample procedure proc (num
integer) begin num 10 end begin
var ch char proc (ch) end.
24
Example Problem

• Write a program that will convert a temperature
  value from Celsius to Fahrenheit.
• The part of the program that performs that actual
  conversion should take the form of a separate
  module.

25
Procedures Putting Together The Case Of
Procedures With Parameters

• temperatureConverter.pas
• program temperatureConverter (input, output)
• procedure celsiusToFahrenheit (celsiusValue
  real)
• var
• fahrenheitValue real
• begin
• fahrenheitValue 9 / 5 celsiusValue 32
• writeln('Temperature in Celsius ',
  celsiusValue02)
• writeln('Temperature in Fahrenheit ',
  fahrenheitValue02)
• end ( Procedure celsiusToFahrenheit )

26
Procedures Putting Together The Case Of
Procedures With Parameters (2)

• begin
• var celsiusValue real
• writeln
• writeln('This program will convert a given
  temperature from a Celsius')
• writeln('value to a Fahrenheit value.')
• write(Enter a temperature in Celsius ')
• readln(celsiusValue)
• writeln
• celsiusToFahrenheit(celsiusValue)
• writeln('Thank you and come again.')
• end. ( Program )

27
Pass by ______ vs. Pass by __________

• Each _______ parameter is ____________ to the
  _______ of the corresponding ____________
  parameter. Called ________________________.

28
Pass by ______ vs. Pass by __________

• Let actP be actual and formP be formal
• Pass by __________
• actP and formP refer to __________ memory
  locations
• ________ of actPs ______________ to formPs
  _______
• changes to formP are __________ to the caller
  (i.e. actP)
• Pass by Reference
• actP and formP refer to __________ memory
  location
• the _______ for formP is ____________________ for
  actP
• changes to formP are __________ to the caller
  (i.e. actP)
• By default, Pascal passes variables by ________.
  However, well see how to make it pass by
  _________________.

29
Pass by ______ vs. Pass by __________

• procedure larger(iinteger jinteger
  kinteger)begin if (iltj) then i j
  k iend
• Suppose that larger is called with
• a 3 b 5 larger(a,b,c)
• After calling larger and passing by __________,
  then a 3, b 5, c 5
• After calling larger if passing by __________,
  then a 5, b 5, c 5

30
Stack Frames

• When a method begins executing, space on the
  ________, called a _____________, is ____________
  for it, to hold
• formal parameters
• local variables declared in the method
• return value (for functions)
• When the method finishes __________, the _______
  frame is ______________, and the formal
  parameters and local variables are
  _______________________.

The program code in the module executes (the
variables are used to _________________________)
31
Stack Frames Example