03 iec t1_s1_plt_session_03
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Installing Windows XP Professional Using Attended Installation
Slide 1 of 29Session 3Ver. 1.0
Programming Logic and Techniques
In this session, you will learn to:Use the dry run table
Identify repetitive processes
Identify modular approach to programming
Objectives
Installing Windows XP Professional Using Attended Installation
Slide 2 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Helps you do a logic check
Understand the flow of control in a flowchart
Evaluate the output of the program with a set of sample values
Provides a step by step evaluation of values in the variables of the program
Using Dry Run
Installing Windows XP Professional Using Attended Installation
Slide 3 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Example:All candidates have to take three tests. A candidate is selected for the interview round based on the scores of all the three tests. The individual score in each test has to be greater than 75 and the average score across the three tests should be a minimum of 80. The call letter for the interview is to be sent to candidates who have been selected and a rejection letter is to be sent to the rest. Represent the logic for the above process by using a flowchart.
Using Dry Run (Contd.)
Installing Windows XP Professional Using Attended Installation
Slide 4 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Flowchart to select a candidate
Using Dry Run (Contd.)
Start
Stop
Declare Variables
Accept Values and Calculate nAverage
IsnAverage>= 80 AND nTest1 > 75 AND nTest2 > 75 AND nTest3 > 75 ?
No
Yes
Display “Interview call letter to be sent”
Display “ Rejectionletter to be sent”
Installing Windows XP Professional Using Attended Installation
Slide 5 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Dry Run Table:
S.No. nTest1 nTest2 nTest 3 nAverage Output
1. 95 90 88 91 Interview call letter to be sent
2. 80 77 83 80 Interview call letter to be sent
3. 90 92 74 85.33 Rejection letter to be sent
4. 76 76 76 76 Rejection letter to be sent
Using Dry Run (Contd.)
Installing Windows XP Professional Using Attended Installation
Slide 6 of 29Session 3Ver. 1.0
Programming Logic and Techniques
An important characteristic of a computer is its ability to execute a series of instructions repeatedly.
A loop is a sequence of instructions that will be repeated more than once.
A loop performs steps in a specified sequence.
There are two types of loops: fixed loops where the number of repetitions is known
variable loops where the number of repetitions is not known
Iteration
Installing Windows XP Professional Using Attended Installation
Slide 7 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Example:Flowchart to display the sum of ten numbers
Iteration (Contd.)
Start
Stop
numeric nNum, nSum, nCounter
Accept nNum
Is nCounter<10 ?
NoYes
nCounter=0 nSum=0
nSum=nSum+nNum
nCounter=nCounter+1
Display nSum
Installing Windows XP Professional Using Attended Installation
Slide 8 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Dry Run Table:
Iteration (Contd.)
S. No. nNum nSum nCounter Output
0. - 0 0
1. 5 5 1
2. 12 17 2
3. 7 24 3
4. 6 30 4
5. 2 32 5
6. 10 42 6
7. 8 50 7
8. 3 53 8
9. 16 69 9
10. 4 73 10 73
Installing Windows XP Professional Using Attended Installation
Slide 9 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Example:You have been assigned the responsibility of generating an address list of all the people working in your office. For each person, you will need to accept the name, address, and the telephone number and print a list containing the collated details.
Iteration (Contd.)
Installing Windows XP Professional Using Attended Installation
Slide 10 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Flowchart segment to display employee details of 25 people
Iteration (Contd.)
No
Stop
nCounter = 1
Accept cName
Is nCounter<=25?
Yes
nCounter=nCounter+1
Display cName, cAddress, cTelno
Accept cAddress
Accept cTelno
Installing Windows XP Professional Using Attended Installation
Slide 11 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Example:Let us look at the same example of preparing the test performance report in the decision-making section again. Now, apart from finding out whether a candidate has to be sent a call letter or a rejection letter, we also have to calculate the number of candidates who have been sent interview call letters and the number of candidates who have been sent rejection letters, using a flowchart.
Iteration (Contd.)
Installing Windows XP Professional Using Attended Installation
Slide 12 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Process
Flowchart to calculate the total number of call letters and rejection letters sent
Iteration (Contd.)
Start
Variable Declaration
Accept Values
IsnAverage >=80 AND
nTest1 > 75 ANDnTest2 > 75 AND
nTest3 > 75 ?
No
Yes
nTotReject=nTotReject+1
nTotSelect=nTotSelect+1
A B
Installing Windows XP Professional Using Attended Installation
Slide 13 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Flowchart to calculate the total number of call letters and rejection letters sent (Contd.)
Iteration (Contd.)
Is cChoice = “Y”?
Yes
No
Display nTotSelect Display nTotReject
A B
Accept cChoice
Display “Any more candidates (Y/N)? ”
Stop
Installing Windows XP Professional Using Attended Installation
Slide 14 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Iteration (Contd.)
S. No. nTest1 nTest2 nTest3 nAverage Output
1. 95 90 88 91 nTotSelect is incremented by 1.
2. 80 77 83 80 nTotSelect is incremented by 1.
3. 90 92 74 85.33 nTotReject is incremented by 1.
4. 76 76 76 76 nTotReject is incremented by 1.
Dry Run Table:
Installing Windows XP Professional Using Attended Installation
Slide 15 of 29Session 3Ver. 1.0
Programming Logic and Techniques
A program needs to be amended periodically to respond to changing conditions or requirements.
This encouraged programmers to adopt a more disciplined approach to program writing.
The techniques that were adopted are known as modularor structured programming techniques.
Modular programming includes features that are designed not only to solve the problem at hand but also to make the logic clear to someone reading the program.
Identifying Modular Approach to Programming
Installing Windows XP Professional Using Attended Installation
Slide 16 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Long, continuous programs can be broken up into a series of individual modules that are related to each other in a specified manner.
Identifying Modular Approach to Programming (Contd.)
Module1 Module2 Module3
Main Program
Installing Windows XP Professional Using Attended Installation
Slide 17 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Add
Return
Add
Start
Stop
Display nSum
numeric nNum1,nNum2, nNum3, nSum
nSum=nNum1 + nNum2 + nNum3Accept nNum1,
nNum2, nNum3
Example:Flowchart to show modular programming
Identifying Modular Approach to Programming (Contd.)
Installing Windows XP Professional Using Attended Installation
Slide 18 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Example:Accept the test scores for 10 students and display their individual averages. The scores of the students cannot be negative.
The table shows the variables used in the flowchart.
Identifying Modular Approach to Programming (Contd.)
Variable Data Type Variable Name
Student Name character cStudentName
Score of Test 1 numeric nTest1
Score of Test 2 numeric nTest2
Score of Test 3 numeric nTest3
Average of Test Scores numeric nAverage
Installing Windows XP Professional Using Attended Installation
Slide 19 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Flowchart to calculate average marks of 10 students
Return
Accept cStudentName
Average
nAverage=(nTest1+nTest2 +nTest3) / 3
Return
Accept
Accept nTest1
Accept nTest2
Accept nTest3
Display “Test score cannot be less than zero”
IsnTest1>=0 ANDnTest2>=0 AND
nTest3>=0 ?
No
Yes
Average
Display cStudentName, nAverage
Accept
Identifying Modular Approach to Programming (Contd.)
Installing Windows XP Professional Using Attended Installation
Slide 20 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Example:The total expenditure on salaries for the month needs to be calculated. As per company policy an employee receives a minimum of $500. Depict the logic for automating the task by using flowcharts.
The table shows the variables used in the flowchart.
Variable Data Type Variable Name
Employee code character cEmpCode
Employee salary numeric nSalary
Total salary numeric nTotSalary
Choice character cChoice
Identifying Modular Approach to Programming (Contd.)
Installing Windows XP Professional Using Attended Installation
Slide 21 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Flowchart to calculate total monthly expenditure on salaries
Summation
Accept
IscChoice = “Y” ?
No
Yes
Display ”Salary cannotbe less than $500”
Accept nSalary
Accept
IsnSalary >=500 ?
Yes
NoReturn
nTotSalary=nTotSalary+nSalary
Summation
Return
Identifying Modular Approach to Programming (Contd.)
Installing Windows XP Professional Using Attended Installation
Slide 22 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Identifying Modular Approach to Programming (Contd.)
S. No. nSalary nTotSalary Output
1. - 0
2. 4500 4500
3. 5500 10000
4. 3400 13400
5. 5600 19000
6. 3000 22000
7. 5000 27000
8. 450 27000 Salary cannot be less than $500
9. 9000 36000
10. 8900 44900
11. 4500 49400 49400
Dry Run Table:
Installing Windows XP Professional Using Attended Installation
Slide 23 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Exercises
Installing Windows XP Professional Using Attended Installation
Slide 24 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Draw a flowchart to print the product of the first 10 even numbers.
Exercise 1
Installing Windows XP Professional Using Attended Installation
Slide 25 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Draw a flowchart to accept 50 numbers and also display the total number of odd and even numbers.
Exercise 2
Installing Windows XP Professional Using Attended Installation
Slide 26 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Exercise 3
Draw a flowchart to display the highest of any 10 numbers entered.
Installing Windows XP Professional Using Attended Installation
Slide 27 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Exercise 4
Draw a flowchart that accepts input from a user and displays the result, depending on whether the user wishes to multiply or divide the numbers provided as input. The Multiply module of the program can multiply maximum of three numbers. The Divide module of the program should check that the denominator should not be zero.
Installing Windows XP Professional Using Attended Installation
Slide 28 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Summary
In this session, you learned that:The concept of dry run will help you perform a logic check and understand the flow of control in a flowchart.
A loop is a sequence of instructions that will be repeated more than once.
A loop performs steps in a specified sequence.
There are two types of loops:Fixed loops where the number of repetitions is known
Variable loops where the number of repetitions is not known
Installing Windows XP Professional Using Attended Installation
Slide 29 of 29Session 3Ver. 1.0
Programming Logic and Techniques
Statements within a loop will be executed repeatedly until the condition becomes false.
The structured programming technique is a disciplined approach to program writing.
A large program can be divided into several modules, where each module performs a specific task. A module is also called a procedure.
A procedure or a module is invoked from the main program and the control is returned from the procedure to the main program by using the return statement.
Summary (Contd.)
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