1 Introduction to Flowcharting

2 Writing a program Defining the problem –Write down what the program will do Planning –Write down the steps, draw a flowchart Programming –Coding, including errors correction, testing Documenting –Adding comments Implementing –Improvement, making the program better

3 Objective A program can be divided into 3 parts: –Input data –Processing data – Calculation, etc. –Output information/results Input Processing Output

4 Arrows From Top to Bottom & from Left to Right Make turn Join together

5 What is a Flowchart? A flowchart is a diagram that depicts the “flow” of a program. A diagram made up of symbols of various shapes connected by arrows. Those symbols indicate either actions to be taken or decisions to be made. It helps us planning & programming. The figure shown here is a flowchart for a pay-calculating program. START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END

6 Basic Flowchart Symbols Notice there are three types of symbols in this flowchart: –rounded rectangles –parallelograms –a rectangle Each symbol represents a different type of operation. START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Rounded Rectangle Parallelogram Rectangle Rounded Rectangle

7 Basic Flowchart Symbols Terminals –represented by rounded rectangles –indicate a starting or ending point START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Terminal STARTEND Terminal

8 Basic Flowchart Symbols Input/Output Operations –represented by parallelograms –indicate an input or output operation START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Display message “How many hours did you work?” Read Hours Input/Output Operation

9 Basic Flowchart Symbols Processes –represented by rectangles –indicates a process such as a mathematical computation or variable assignment START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Multiply Hours by PayRate. Store result in GrossPay. Process

10 Stepping Through the Flowchart START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Variable Contents: Hours: ? PayRate: ? GrossPay: ? Stepping Through the Flowchart In the next seven slides we will step through each symbol in the flowchart. We will show the program output and the contents of the variables.

11 Stepping Through the Flowchart How many hours did you work? START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Variable Contents: Hours: ? PayRate: ? GrossPay: ? Step 1: An Output Operation Stepping Through the Flowchart Screen Output

12 Stepping Through the Flowchart How many hours did you work? 40 START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Variable Contents: Hours: 40 PayRate: ? GrossPay: ? Step 2: An Input Operation (User types 40) Stepping Through the Flowchart The value 40 is stored in Hours.

13 Stepping Through the Flowchart How much do you get paid per hour? START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Variable Contents: Hours: 40 PayRate: ? GrossPay: ? Step 3: An Output Operation Stepping Through the Flowchart Screen Output

14 Stepping Through the Flowchart How much do you get paid per hour? 20 START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Variable Contents: Hours: 40 PayRate: 20 GrossPay: ? Step 4: Input Operation (User types 20) Stepping Through the Flowchart The value 20 is stored in PayRate.

15 How much do you get paid per hour? 20 START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Variable Contents: Hours: 40 PayRate: 20 GrossPay: 800 Step 5: The product of Hours times PayRate is stored in GrossPay Stepping Through the Flowchart The value 800 is stored in GrossPay.

16 Stepping Through the Flowchart Your gross pay is 800 START Display message “How many hours did you work?” Read Hours Display message “How much do you get paid per hour?” Read PayRate Multiply Hours by PayRate. Store result in GrossPay. Display GrossPay END Variable Contents: Hours: 40 PayRate: 20 GrossPay: 800 Step 6: An Output Operation Screen Output

17 Four Flowchart Structures Sequence (TODAY) Decision Repetition Case

18 Sequence Structure A series of actions are performed in sequence The pay-calculating example was a sequence flowchart.

19 Connectors Sometimes a flowchart will not fit on one page. A connector (represented by a small circle) allows you to connect two flowchart segments. A

20 Connectors A A START END The “A” connector indicates that the second flowchart segment begins where the first segment ends.

21 Review What do each of the following symbols represent? (Answer on next slide)

22 Answer What do each of the following symbols represent? Terminal Input/Output Operation Process

23 Review Name the four flowchart structures. (Answer on next slide)

24 Answer Sequence Decision Repetition Case

25 Flowcharting Problems Write out the steps to solve the problem, then draw the diagram 1.Flowchart a program to input the radius of a circle, and then calculate and print the area. The formula is Area = Pi * Radius 2 2.Flowchart a program that will input four marks and calculate the average. 3.Flowchart a program that will take a temperature in Fahrenheit (F) convert it to Centigrade (C) The formulas are below. C = ( F - 32) / 1.8 –Output the results with a message that states: “ ___ degrees C is equal to ___ degrees F”