Lecture 5C for Section-C

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CS141-Programming Fundamentals-Jameel Ahmad 1

CS141-Programming Fundamentals-Jameel Ahmad

CS-141 Programming Fundamentals

Lecture-5C

Counter-Controlled Repetition

Sentinel-Controlled Repetition

Nested Control Structures

Jameel AhmadAssistant Professor

[email protected]

Department of Electrical Engineering

University of Management and Technology

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CS141-Programming Fundamentals-Jameel Ahmad

1. Lab 2 on Friday Nov 04, 2011

2. Quiz 2 on Friday Nov 04, 2011

3. Teaching Assistants (TAs) for class

1) Abdur Rehman: Phone No 0334-471-4413 Email: [email protected]

2) Fazalur Rehman Sharif: Phone No 0334-324-8611 Email:[email protected]. Home work Grader:

Rehan Afzal Phone No 0345-451-3577

Announcements for section C

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C How to Program, 6/e


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CS141-Programming Fundamentals-

Jameel Ahmad 5

CS141-Programming Fundamentals-Jameel Ahmad 6

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Chapter 3 - Structured

Program Development

Outline3.1 C Data Types3.2 Algorithms3.3 Pseudocode3.4 Control Structures

3.5 The If Selection Statement3.6 The IfElse Selection Statement3.7 The While Repetition Statement3.8 Formulating Algorithms: Case Study 1 (Counter-Controlled

Repetition)

3.9 Formulating Algorithms with Top-down, Stepwise

Refinement: Case Study 2 (Sentinel-Controlled Repetition)3.10 Formulating Algorithms with Top-down, Stepwise

Refinement: Case Study 3 (Nested Control Structures)3.11 Assignment Operators3.12 Increment and Decrement Operators

CS141-Programming Fundamentals-

Jameel Ahmad

CS141 Programming Fundamentals

while ( expression or condition){

Single statement

orBlock of statements;}

While Repetition structureWhile Repetition structureWhile Repetition structureWhile Repetition structure

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Copyright 19922004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved .

CS141 Programming Fundamentals 13

The while Loop (continued)

Infinite loop: continues to execute endlessly

Can be avoided by including statements in the

loop body that assure exit condition will

eventually be false

One-Way (if) Selection

CS141-Programming Fundamentals-Jameel

Ahmad14

The syntax of one-way selection is:

if (expression)

statement

Statement is executed if the value of the expression is true

Statement is bypassed if the value is false; program goes

to the next statement

One-Way (if) Selection (continued)


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The expression is sometimes called a decision maker because

it decides whether to execute the statement that follows it

The statement following the expression is sometimes called

the action statement

The expression is usually a logical expression

The statement is any C++ statement

if is a reserved word


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3.9 Formulating Algorithms with Top-Down, Stepwise Refinement

Top-down, stepwise refinement

Begin with a pseudocode representation of the top:

Determine the class average for the quiz

Divide top into smaller tasks and list them in order:

Initialize variablesInput, sum and count the quiz gradesCalculate and print the class average

Many programs have three phases: Initialization: initializes the program variables

Processing: inputs data values and adjusts programvariables accordingly

Termination: calculates and prints the final results


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3.9 Formulating Algorithms with Top-

Down, Stepwise Refinement

Refine the initialization phase fromInitialize

variables to:Initialize total to zero

Initialize counter to zero

RefineInput, sum and count the quiz grades to

Input the first grade (possibly the sentinel)While the user has not as yet entered the sentinel

Add this grade into the running total

Add one to the grade counter

Input the next grade (possibly the sentinel)


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3.9 Formulating Algorithms with Top-Down, Stepwise Refinement

Refine Calculate and print the class average toIf the counter is not equal to zero

Set the average to the total divided by the counter

Print the average

else

Print No grades were entered


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3.9 Formulating Algorithms with Top-

Down, Stepwise Refinement

Initialize total to zero

Initialize counter to zero

Input the first grade

While the user has not as yet entered the sentinel

Add this grade into the running totalAdd one to the grade counter

Input the next grade (possibly the sentinel)

If the counter is not equal to zero

Set the average to the total divided by the counter

Print the average

else

Print No grades were entered


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Algorithm Design

Set precision to two decimal places

Prompt user for account number and customer type

If customer type is R or r

Prompt user for number of premium channels

Compute and print the bill

If customer type is B or b

Prompt user for number of basic service connections andnumber of premium channels

Compute and print the bill ProgrammingExample-1

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Variables

ProgrammingExample-1

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Named Constants

Pro

grammingExample-1

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Formulas

Billing for residential customers:

amountDue = RES_BILL_PROC_FEES +

RES_BASIC_SERV_COST

+ numOfPremChannels *

RES_COST_PREM_CHANNEL;


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Formulas (continued)

Billing for business customers:

if (numOfBasicServConn


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Programming Example-2 A local bank in your town needs a program to calculate a

customers checking account balance at the end of each

month

Data are stored in a file in the following form:

467343 23750.40

W 250.00

D 1200

W 75.00

I 120.74

Pro

grammingExample-2

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Programming Example-2

(continued) The first line of data shows the account number followed by the

account balance at the beginning of the month

Thereafter each line has two entries:

Transaction code

Transaction amount

Transaction codes W or w means withdrawal

D or d means deposit

I or i means interest paid by the bankProgrammingExample-2

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Programming Example

(continued) Program updates balance after each transaction

During the month, if at any time the balance goes below$1000.00, a $25.00 service fee is charged

Pro

grammingExample-2

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Programming Example

(continued)

Program prints the following information:

Account number

Balance at the beginning of the month

Balance at the end of the month

Interest paid by the bank

Total amount of deposit

Number of deposits

Total amount of withdrawal

Number of withdrawals

Service charge if any


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Variables


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Named Constants

ProgrammingExam

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Steps1. Declare variables as discussed previously

2. Initialize variables

isServicedCharged is initialized to false

Read the beginning balance in the variablebeginningBalance from the file and initialize the variable

accountBalance to the value of the variable

beginningBalance

Since the data will be read from a file, you need to open inputfile


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Steps (continued)

3. Get account number and starting balance

infile >> acctNumber >> beginningBalance;

4. Get transaction code and transaction amount

infile >> transactionCode

>> transactionAmount;

5. Analyze transaction code and update appropriate

variablesProgrammingExam

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Steps (continued)6. Repeat Steps 4 and 5 until there is no more data

Since the number of entries in the input file is not known, usean EOF-controlled while loop

7. Print the result


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Main Algorithm

1. Declare and initialize variables

2. Open input file

3. If input file does not exist, exit

4. Open output file

5. Output numbers in appropriate formats

6. Read accountNumber and beginningBalance

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Main Algorithm (continued)7. Set accountBalance to beginningBalance

8. Read transactionCodeand transactionAmount

9. while (not end of input file) if transactionCode is 'D' or 'd'

i. AddtransactionAmount to

accountBalance

ii. Increment numberOfDeposits

if transactionCode is 'I' or 'i' i. Add transactionAmount to accountBalance

ii. Add transactionAmount to interestPaid


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Main Algorithm (continued)

IftransactionCode is 'W' or 'w'

i. Subtract transactionAmount from

accountBalance

ii. Increment numberOfWithdrawals

iii. if (accountBalance < MINIMUM_BALANCE

&& !isServicedCharged)1. Subtract SERVICE_CHARGE from accountBalance

2. Set isServiceCharged totrue

IftransactionCode is other than 'D', 'd', 'I','i', 'W', or 'w', output an error message

10. Output the results

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Write C code for two programming Examples

Will be discussed in next lectures

CS141-Programming

Fundam

entals-JameelAhmad

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Lecture 5C for Section-C

Documents

Transcript of Lecture 5C for Section-C