Sem1 plt xp_03
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The document discusses iterations, modular programming, and flowcharts. It explains how to use dry run tables to evaluate a program's logic and output. It also describes how to represent repetitive processes and complex conditions using loops and modular structures in flowcharts. Breaking problems into smaller modules is an important part of the structured programming technique.
Sem1 plt xp_03
- 1. Understanding Iterations and Implementing Modular Programming Objectives In this lesson, you will learn to: Use the dry run table Identify repetitive processes Represent complex conditions and iterations by using flowcharts Break down a problem into modules ©NIIT PLT/Lesson 3/Slide 1 of 30
- 2. Understanding Iterations and Implementing Modular Programming Dry Run Helps you to 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 ©NIIT PLT/Lesson 3/Slide 2 of 30
- 3. Understanding Iterations and Implementing Modular Programming Dry Run (Contd.) 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. ©NIIT PLT/Lesson 3/Slide 3 of 30
- 4. Understanding Iterations and Implementing Modular Programming Variables Variable Data Type Variable Name Employee Name character cName Employee Address character cAddress Telephone Number character cTelno Counter numeric nCounter ©NIIT PLT/Lesson 3/Slide 4 of 30
- 5. Understanding Iterations and Implementing Modular Programming Flowchart to Select a Candidate Start Declare Variables Accept Variables and Calculate nAverage Is nAverage= 80 AND No Display “ Rejection nTest1 75 AND letter to be sent” nTest2 75 AND nTest3 75 ? Yes Display “ Interview call letter to be sent” Stop ©NIIT PLT/Lesson 3/Slide 5 of 30
- 6. Understanding Iterations and Implementing Modular Programming 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. ©NIIT PLT/Lesson 3/Slide 6 of 30
- 7. Understanding Iterations and Implementing Modular Programming Iteration 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 ©NIIT PLT/Lesson 3/Slide 7 of 30
- 8. Understanding Iterations and Implementing Modular Programming Example Flowchart to Display the Sum of Ten Numbers Start numeric nNum, nSum, nCounter nCounter=0 nSum=0 Accept nNum nSum=nSum+nNum nCounter=nCounter+1 Yes Is No nCounter10 ? Display nSum Stop ©NIIT PLT/Lesson 3/Slide 8 of 30
- 9. Understanding Iterations and Implementing Modular Programming Dry Run Table S. No. nNum nSum nCounter Output 1. - 0 0 2. 5 5 1 3. 12 17 2 4. 7 24 3 5. 6 30 4 6. 2 32 5 7. 10 42 6 8. 8 50 7 9. 3 53 8 10. 16 69 9 11. 4 73 10 73 ©NIIT PLT/Lesson 3/Slide 9 of 30
- 10. Understanding Iterations and Implementing Modular Programming 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. ©NIIT PLT/Lesson 3/Slide 10 of 30
- 11. Understanding Iterations and Implementing Modular Programming Flowchart Segment to Display Employee Details of 25 People nCounter = 1 Is No nCounter=25? Yes Stop Accept cName Accept cAddress Accept cTelno Display cName, cAddress, cTelno nCounter=nCounter+ 1 ©NIIT PLT/Lesson 3/Slide 11 of 30
- 12. Understanding Iterations and Implementing Modular Programming 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. ©NIIT PLT/Lesson 3/Slide 12 of 30
- 13. Understanding Iterations and Implementing Modular Programming Flowchart to Calculate the Total Number of Call Letters and Rejection Letters Sent Start Variable Declaration Accept Values Is nAverage =80 AND No nTest1 75 AND nTotReject=nTotReject+1 nTest2 75 AND nTest3 75 ? Yes nTotSelect=nTotSelect+1 A B ©NIIT PLT/Lesson 3/Slide 13 of 30
- 14. Understanding Iterations and Implementing Modular Programming Flowchart to Calculate the Total Number of Call Letters and Rejection Letters Sent (Contd.) B A Display “Any more candidates (Y/N)? ” Accept cChoice Is No cChoice = “Y”? Yes Display nTotSelect Display nTotReject Stop ©NIIT PLT/Lesson 3/Slide 14 of 30
- 15. Understanding Iterations and Implementing Modular Programming Dry Run Table S. No. nTest1 nTest2 nTest2 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. ©NIIT PLT/Lesson 3/Slide 15 of 30
- 16. Understanding Iterations and Implementing Modular Programming Modular Approach to Programming 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 structured programming techniques. Structured 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 ©NIIT PLT/Lesson 3/Slide 16 of 30
- 17. Understanding Iterations and Implementing Modular Programming Modular Approach to Programming (Contd.) Long, continuous programs can be broken up into a series of individual modules that are related to each other in a specified manner. Main Program Module1 Module2 Module3 ©NIIT PLT/Lesson 3/Slide 17 of 30
- 18. Understanding Iterations and Implementing Modular Programming Flowchart to Show Modular Programming Start numeric nNum1, Add nNum2, nNum3, nSum nSum=nNum1 + nNum2 Accept nNum1, + nNum3 nNum2, nNum3 Return Add Display nSum Stop ©NIIT PLT/Lesson 3/Slide 18 of 30
- 19. Understanding Iterations and Implementing Modular Programming Example Accept the test scores for ten students and display their individual averages. The scores of the students cannot be negative. The table shows the variables used in the flowchart. 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 ©NIIT PLT/Lesson 3/Slide 19 of 30
- 20. Understanding Iterations and Implementing Modular Programming Flowchart to Calculate Average Marks of Ten Students Accept Accept cStudentName Accept Average Accept nTest1 Average nAverage=(nTest1+nTest2 Accept nTest2 +nTest3) / 3 Display cStudentName, Accept nTest3 Return nAverage Is nTest1=0 AND Yes nTest2=0 AND nTest3=0 ? Return No Display “Test score cannot be less than zero” ©NIIT PLT/Lesson 3/Slide 20 of 30
- 21. Understanding Iterations and Implementing Modular Programming 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. Program Variables to be used are: Variable Data Type Variable Name Employee Code character cEmpCode Employee salary numeric nSalary Total salary numeric nTotSalary Choice character cChoice ©NIIT PLT/Lesson 3/Slide 21 of 30
- 22. Understanding Iterations and Implementing Modular Programming Flowchart to Calculate Total Monthly Expenditure on Salaries Accept Is No Summation cChoice = “Y” ? Accept nSalary Yes nTotSalary=nTotSalary+nSalary Is Yes Accept nSalary =500 ? Return Return No Summation Display”Salary cannot be less than $500” ©NIIT PLT/Lesson 3/Slide 22 of 30
- 23. Understanding Iterations and Implementing Modular Programming Example Dry Run 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 ©NIIT PLT/Lesson 3/Slide 23 of 30
- 24. Understanding Iterations and Implementing Modular Programming Problem Statement 3.P.1 Draw a flowchart to print the product of the first 10 even numbers. ©NIIT PLT/Lesson 3/Slide 24 of 30
- 25. Understanding Iterations and Implementing Modular Programming Problem Statement 3.P.2 Draw a flowchart to accept 50 numbers and also display the total number of odd and even numbers. ©NIIT PLT/Lesson 3/Slide 25 of 30
- 26. Understanding Iterations and Implementing Modular Programming Problem Statement 3.P.3 Draw a flowchart to display the highest of any 10 numbers entered. ©NIIT PLT/Lesson 3/Slide 26 of 30
- 27. Understanding Iterations and Implementing Modular Programming Problem Statement 3.P.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. ©NIIT PLT/Lesson 3/Slide 27 of 30
- 28. Understanding Iterations and Implementing Modular Programming Problem Statement 3.P.5 How many names will the following flowchart print? nCtr = 0 Accept cName Display cName No Is nCtr =10 ? Yes Stop ©NIIT PLT/Lesson 3/Slide 28 of 30
- 29. Understanding Iterations and Implementing Modular Programming Summary In this lesson, 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 ©NIIT PLT/Lesson 3/Slide 29 of 30
- 30. Understanding Iterations and Implementing Modular Programming Summary (Contd.) ® Variable loops where the number of repetitions is not known 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 ©NIIT PLT/Lesson 3/Slide 30 of 30