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CS 240 Computer Programming 1 Flowcharts 1

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Algorithm 2 a step-by-step method for solving a problem or doing a task. An informal definition of an algorithm is:

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Algorithm 3 A step-by-step problem-solving procedure An algorithm is a sequence of unambiguous instructions for solving a problem. The number of steps of an algorithm will be countable and finite. It is a sequence of instructions (or set of instructions) to make a program more readable; a process used to answer a question.

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How to understand the problem? 4 Define the problem Analyze the problem Develop an algorithm/method of solution Write a computer program corresponding to the algorithm Test and debug the program Document the program (how it works and how to use it)

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5 Flowcharts Tools There are two commonly used tools to help to document program logic (the algorithm) Pseudo code

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Flowchart 6 The production flowchart is a visual representation of the sequence of the program. It shows what comes first, second, third, etc Definition A flowchart indicates: The steps to be taken in order to solve a problem. The order or the sequence of these steps.

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7 Flowchart Rules 1. Use only one start and one stop per flowchart, --that is, one way in and one way out of the flowchart. 2. The logic flow of the solution is displayed from top to bottom and from left to right. 3. Use the appropriate symbol for each type of operation. 4. Use arrows when moving to another part of the flowchart rather than lines. 5. Do not leave dead-ends--that is, a part of a question unanswered.

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Symbols 8 Symbol Description TERMINAL - To start or end a flowchart INPUT / OUTPUT - Used with Read, Input, Print and other I/O commands. PROCESSING - Used for operations done inside the computer. Such as calculations, storing and moving of data. DECISION - Used to ask a question in programming. Questions are Yes/No format (Used with the If Statement). DIRECTION FLOW - Used to connect symbols and to represent the direction of flow. Lines should not cross each other. Arrowheads should be placed at the end close to the symbol. Connector - or joining of two parts of program

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1.Simple sequential Flowchart 9 Construct a flow chart that prints "Hello, World"? Example 1

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1.Simple sequential Flowchart 10 Step 1- Start Algorithm Step 2- Print "Hello, World" Step 3- Stop

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1.Simple sequential Flowchart 11 Start Print “Hello, World” Stop Flowchart

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1.Simple sequential Flowchart 12 Construct a flow chart that finds the sum of two numbers. Example 2

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1.Simple sequential Flowchart 13 C: Sum (A+B) Variables B: Second Number A: First Number Step 3- Read B Algorithm Step 2- Read A Step 1- Start Step 4- Calculate C = A+B Step 5- Print C Step 6- Stop

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1.Simple sequential Flowchart 14 Flowchart Start Read A Read B C= A+B Print C Stop

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1.Simple sequential Flowchart 15 Construct a flow chart that finds the sum, average and product of three numbers. Example 3

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1.Simple sequential Flowchart 16 Z: Third Number Variables Y: Second Number X: First Number Step 3- Calculate S = X+Y+Z Algorithm Step 2- Read X, Y, Z Step 1- Start Step 4- Calculate A = S/3 Step 6- Print S, A, P Step 7- Stop S: Sum (X+Y+Z) A: Average (S/3) P: Product (X*Y*Z) Step 5- Calculate P = X*Y*Z

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1.Simple sequential Flowchart 17 Flowchart Start Read X,Y,Z S= X+Y+Z A=S/3 P=X*Y*Z Print S,A,P Stop

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1.Simple sequential Flowchart 18 Construct a flow chart that finds the difference and the division of two numbers and display the result Example 4

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1.Simple sequential Flowchart 19 D: Difference Variables N2 : Second Number N1 : First Number Step 3- Calculate D = N1-N2 Algorithm Step 2- Read N1, N2 Step 1- Start Step 4- Calculate V = N1/N2 Step 6- Stop V: Division Step 5- Print D,V

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1.Simple sequential Flowchart 20 Flowchart Start Read N1, N2 D= N1 –N2 V=N1/N2 Print D,V Stop

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1.Simple sequential Flowchart 21 Construct a flow chart that finds the circle area and circumference of a circle where R (radius) is given Example 5 Exercise

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1.Simple sequential Flowchart 22 A: Area Variables PI: PI = 3.14 R : Radius Step 3- Calculate A = PI*(R) 2 Algorithm Step 2- Read R Step 1- Start Step 4- Calculate C = 2*PI*R Step 6- Stop C: Circumference Step 5- Print R, A, C

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2. Branched Flowcharts 23 Construct a flow chart for the following function Example 1 F(x) = { XX>=0 -X X<0

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24 Variables X : Number Step 3- if X >=0 then F =X Algorithm Step 2- Read X Step 1- Start Step 4- if X <0 then F =-X Step 6- Stop Step 5- Print F 2. Branched Flowcharts F: function of X

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25 Flowchart 2. Branched Flowcharts Start Read X Print F Stop F=-X F=X X>=0 YES NO

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2. Branched Flowcharts 26 Trace the following flowchart and write the output of it. Example 2 1. When X = When X = -10

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27 Flowchart 2. Branched Flowcharts Start Read X Print X,W Stop W=2*X-1 W=X+1 X? >0 0> =0 W=SIN(X)+5

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28 Result 2. Branched Flowcharts X= 20 W= 21 When X=20 X= -10 W= -21 When X=-10

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2. Branched Flowcharts 29 Draw a flowchart that shows the traffic light processing Example 3 Exercise

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30 Variables C : Traffic light color Step 4- if C is RED then Print STOP Algorithm Step 2- Read C Step 1- Start Step 5- if C is YELLOW then Print WAIT Step 7- Stop Step 6- if C is GREEN then Print PASS 2. Branched Flowcharts Step 3- make a Decision (what is c)

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31 Trace the following flowchart and write the output of it. Example 1 3. Loop Flowcharts

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32 Flowchart 3. Loop Flowcharts Start Stop N=N+3 While N>=7 F T N=1 Print N

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33 Result 3. Loop Flowcharts NLoop

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34 Trace the following flowchart and write the output of it. Example 2 3. Loop Flowcharts

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35 Flowchart 3. Loop Flowcharts Start Print avg Stop Sum= X + Sum Increment i avg=Sum/10 While i<10 F T i=0 Sum=0 Read X

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36 Result 3. Loop Flowcharts LoopRead XSumi Avg =50/10 =5

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