1 Introduction to Flowcharting. 2 Writing a program Defining the problem –Write down what the...
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Transcript of 1 Introduction to Flowcharting. 2 Writing a program Defining the problem –Write down what the...
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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
START
END 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.
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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
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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: 40PayRate: ?GrossPay: ?
Step 2: An Input Operation
(User types 40)
Stepping Through the Flowchart
The value 40 is stored in Hours.
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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: 40PayRate: ?GrossPay: ?
Step 3: An Output Operation
Stepping Through the Flowchart
Screen Output
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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: 40PayRate: 20GrossPay: ?
Step 4: Input Operation
(User types 20)
Stepping Through the Flowchart
The value 20 is stored in PayRate.
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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: 40PayRate: 20GrossPay: 800
Step 5: The product of Hours times PayRate is stored in GrossPay
Stepping Through the Flowchart
The value 800 is stored in GrossPay.
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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: 40PayRate: 20GrossPay: 800
Step 6: An Output Operation
Screen Output
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Four Flowchart Structures
• Sequence (TODAY)
• Decision
• Repetition
• Case
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Sequence Structure
• A series of actions are performed in sequence• The pay-calculating example was a sequence
flowchart.
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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
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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)
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Answer
• Sequence• Decision• Repetition• Case
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Flowcharting ProblemsWrite out the steps to solve the problem, then draw the diagram1.Flowchart a program to input the radius of a circle, and then calculate and print the area. The formula is Area = Pi * Radius2
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”
