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CC111 Lec#6 : Flow Charts 1 Flow Charts Reference :Understanding Computers Chapter 13.

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Presentation on theme: "CC111 Lec#6 : Flow Charts 1 Flow Charts Reference :Understanding Computers Chapter 13."— Presentation transcript:

1 CC111 Lec#6 : Flow Charts 1 Flow Charts Reference :Understanding Computers Chapter 13

2 CC111 Lec#6 : Flow Charts 2 DefinitionsDefinitions Flowchart: Flowchart: is a diagrammatic representation that illustrates the sequence of operations to be performed to get the solution of a problem.

3 CC111 Lec#6 : Flow Charts 3 Standard Symbols Used A1 Off-page Connector ? Yes No Condition Calculate Variables Process Rectangle A On-Page Connector PrintResults Input/Output Start Or Stop Process Start

4 CC111 Lec#6 : Flow Charts 4 How to Write a Program? 1.Start 2.Define Problem to Solve 3.Think of an Algorithm 4.Think of a Technique for the Solution 5.Write Solution on a Piece of Paper 6.If not Finished Repeat Steps 4 and 5 7.Write Code and Program 8.Debug and Test 9.If not Finished Repeat Steps 7 and 8 10.Stop

5 CC111 Lec#6 : Flow Charts 5 How to Write a Program ?(flowchart) Define Problem to Solve Stop Think of an Algorithm (Technique for the solution) Idea!!!! Write it down on a piece of paper (before you forget it!!!) Write Code and Program Job Done? Debug and Test Job Done? Start Think of a Technique for the solution No Yes No

6 CC111 Lec#6 : Flow Charts 6 Definitions An Algorithm Is a complete step-by-step procedure for solving a problem or accomplishing a task. ( Where the algorithm is represented by drawing “Flowcharts” ) A computer program makes use of algorithms.

7 CC111 Lec#6 : Flow Charts 7 Basic Flow Chart Operations 1.Simple Sequence 2.Selection Pattern 3.Loop Pattern All computer instructions are based on four basic processing patterns:

8 CC111 Lec#6 : Flow Charts 8 1.Simple Sequence  Logic involves executing instructions one statement after another, in the order presented by the program.  This is the simplest and most-used pattern.  The computer assumes that all instructions are to be executed in this order unless the program presents other instructions.

9 CC111 Lec#6 : Flow Charts 9 Read Names Compare with Criteria Print Eligible Names Basic Operations of Flow Charts (Simple Sequence)

10 CC111 Lec#6 : Flow Charts Selection Pattern  Requires that the computer make a choice among two or more items.  Each choice is based on one of two comparisons a computer can make: true or false (Yes or No).

11 CC111 Lec#6 : Flow Charts 11 Honour Student ? List under Student Loan Yes List under Scholarships No Basic Operations of Flow Charts (Selection Pattern)

12 CC111 Lec#6 : Flow Charts Loop Pattern  Directs the computer to loop back to a previous statement in the program, repeating the same sequence over again, usually with new data.  By looping, the programmer avoids having to repeat the same set of instructions over and over

13 CC111 Lec#6 : Flow Charts 13 More Names? No Yes Compare with Criteria Print Eligible Names Basic Operations of Flow Charts (Loop Pattern)

14 CC111 Lec#6 : Flow Charts 14  Flowcharts play a vital role in the programming of a problem and are quite helpful in understanding the logic of complicated and lengthy problems.  Once the flowchart is drawn, it becomes easy to write the program in any high level language.  Often we see how flowcharts are helpful in explaining the program to others.  Hence, it is correct to say that a flowchart is a must for the better documentation of a complex program. Uses of Flow Charts

15 CC111 Lec#6 : Flow Charts 15  Flow Charts document processes and interrelationships of process steps  Flow Charts identify actual and ideal paths where any product or process flows  Flow Charts are used to identify problems and potential improvements  Flow Charts can be completed on entire processes assemblies with all components, one person or component through a process, combinations of people and machines, transactions following forms or other documents, etc. Uses of Flow Charts…….

16 CC111 Lec#6 : Flow Charts 16  Communication: Flowcharts are better way of communicating the logic of a system to all concerned.  Effective Analysis: With the help of flowchart, problem can be analysed in more effective way.  Proper Documentation: Program flowcharts serve as a good program documentation, which is needed for various purposes. Advantages of Flow Charts

17 CC111 Lec#6 : Flow Charts 17  Efficient Coding: The flowcharts act as a guide or blueprint during the systems analysis and program development phase.  Proper Debugging: The flowchart helps in debugging process.  Efficient Program Maintenance: The maintenance of operating program becomes easy with the help of flowchart. It helps the programmer to put efforts more efficiently on that part. Advantages of Flow Charts….

18 CC111 Lec#6 : Flow Charts 18  Complex Logic: Sometimes, the program logic is quite complicated. In that case, flowchart becomes complex and clumsy.  Alterations and Modifications: If alterations are required the flowchart may require re-drawing completely.  Reproduction: As the flowchart symbols cannot be typed, reproduction of flowchart becomes a problem.  The Essentials of what Is Done can easily be lost in the technical details of how it is done. Disadvantages of Flow Charts

19 CC111 Lec#6 : Flow Charts 19 A certain Company gives each of its sales people $1,000 at the beginning of each month to cover travel, lodging, and food expenses. At the end of the month, a salesperson must total his/her expense receipts. If the amount is less than $1,000 then the difference must be returned to the company. Case Study - 1

20 CC111 Lec#6 : Flow Charts 20 Here is an algorithm for figuring how much money, if any, must be returned: 1-Total the expense receipts for the month. 2. Subtract the amount of the expense receipts from 1, the remainder is more than 0, return that amount to the company. 3. If the remainder is more than 0, return that amount to the company. Case Study – 1 (Solution)

21 CC111 Lec#6 : Flow Charts 21 Stop Subtract Expenses R <= 1000-E E<1000? Start No Yes Input Expenses E Print You Owe $0 Print You Owe $R Case Study – 1 (Flow Chart)

22 CC111 Lec#6 : Flow Charts 22 What would be the amount to return to the company in this case? Assume the Employee has Spent $1250 Case Study – 1 (Solution 1)

23 CC111 Lec#6 : Flow Charts 23 Stop Subtract Expenses R <= 1000-E E<1000 ? Start No Yes Input Expenses Print You Owe $0 Print You Owe $R E=$1250 Case Study – 1 (Solution 1) R= $0

24 CC111 Lec#6 : Flow Charts 24 What would be the amount to return to the company in this case? Now Assume the Employee has Spent $950 Case Study – 1 (Solution 2)

25 CC111 Lec#6 : Flow Charts 25 Stop Subtract Expenses R = 1000-E E<1000 ? Start No Yes Input Expenses Print You Owe $0 Print You Owe $R Case Study – 1 (Solution 2) R= $50

26 CC111 Lec#6 : Flow Charts 26 Basic Guidelines for Flow Charting  In drawing a proper flowchart, all necessary requirements should be listed out in logical order.  The flowchart should be clear, neat and easy to follow. There should not be any room for ambiguity in understanding the flowchart.  The usual direction of the flow of a procedure or system is from left to right or top to bottom

27 CC111 Lec#6 : Flow Charts 27 Only one flow line should come out from a process symbol. Basic Guidelines for Flow Charting(Cont.)

28 CC111 Lec#6 : Flow Charts 28 Y N ? < = ? > Basic Guidelines for Flow Charting (Cont.) Only one flow line should enter a decision symbol, but two or three flow lines, one for each possible answer, should leave the decision symbol.

29 CC111 Lec#6 : Flow Charts 29 Stop Start Basic Guidelines for Flow Charting (Cont.) Only one flow line is used in conjunction with terminal symbol.

30 CC111 Lec#6 : Flow Charts 30  Write within standard symbols briefly. As necessary, you can use the annotation symbol to describe data or computational steps more clearly.  If the flowchart becomes complex, it is better to use connector symbols to reduce the number of flow lines.  Avoid the intersection of flow lines if you want to make it more effective and better way of communication. Basic Guidelines for Flow Charting (Cont.)

31 CC111 Lec#6 : Flow Charts 31 Basic Guidelines for Flow Charting (Cont.) Ensure that the flowchart has a logical start and finish. It is useful to test the validity of the flowchart by passing through it with a simple test data

32 CC111 Lec#6 : Flow Charts 32. Draw a flowchart to find the sum of first 5 natural numbers. Case Study - 2

33 CC111 Lec#6 : Flow Charts NSum Sum = 0 Stop N = 0 N = N + 1 ? N = 5 Start Sum = Sum + N No Yes Print Sum

34 CC111 Lec#6 : Flow Charts 34 Draw a flowchart to find the largest of three numbers A,B, and C. Case Study - 3

35 CC111 Lec#6 : Flow Charts 35 Stop ? A > B Start No Read A, B, C ? B > C No ? A > C No Print BPrint CPrint APrint C Yes Case Study - 3

36 CC111 Lec#6 : Flow Charts 36 Consider four input cases: 4. A = 5 ; B = 3 ; C = 3 1. A = 5 ; B = 7 ; C = 3 2. A = 5 ; B = 6 ; C = 7 3. A = 5 ; B = 3 ; C = 7 Case Study – 3 - (Solutions)

37 CC111 Lec#6 : Flow Charts 37 Stop ? A > B Start No Read A, B, C ? B > C No ? A > C No Print BPrint CPrint APrint C Yes B = 7 C = 3 A = 5 Case Study – 3 (Solution 1)

38 CC111 Lec#6 : Flow Charts 38 Stop ? A > B Start No Read A, B, C ? B > C No ? A > C No Print BPrint CPrint APrint C Yes B = 6 C = 7 A = 5 Case Study – 3 (Solution 2)

39 CC111 Lec#6 : Flow Charts 39 Stop ? A > B Start No Read A, B, C ? B > C No ? A > C No Print BPrint CPrint APrint C Yes B = 3 C = 7 A = 5 Case Study – 3 (Solution 3)

40 CC111 Lec#6 : Flow Charts 40 Stop ? A > B Start No Read A, B, C ? B > C No ? A > C No Print BPrint CPrint APrint C Yes B = 3 C = 3 A = 5 Case Study – 3 (Solution 4)

41 CC111 Lec#6 : Flow Charts 41 Draw a flowchart for computing factorial N (N!). Where N! = 1 ´ 2 ´ 3 ´ …… N. Test the program for N = 5 Case Study - 4

42 CC111 Lec#6 : Flow Charts iFact Fact = 1 Stop i = 0 i = i + 1 ? i >= N Start Fact = Fact * i No Yes Print Fact Read N N 5 Case Study – 4


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