Pseudocode is a way to describe the steps of an algorithm using plain English instead of a programming language. It allows describing logical steps in a structured format without specifics of syntax. The document provides examples of pseudocode and flowcharts for simple tasks like adding numbers and calculating age. It also explains common symbols used in flowcharts like START/END, INPUT/OUTPUT, PROCESS, and DECISION.

2. What is pseudocode?
 List of steps written in English
 Like the instructions for a recipe
 Must be in the right sequence
 Imagine saying “bake the cake” and then “mix it up”

3. Sample Pseudocode
 Task: add two numbers
 Pseudocode:
 Start
 Get two numbers
 Get first number
 Get second number
 Add them
 Print the answer
 End

4. Invitation to Computer Science,
Java Version, Third Edition 4
Pseudocode
 English language constructs modeled to look like
statements available in most programming
languages
 Steps presented in a structured manner
(numbered, indented, and so on)
 No fixed syntax for most operations is required

5. Invitation to Computer Science,
Java Version, Third Edition 5
Pseudocode (continued)
 Less ambiguous and more readable than natural
language
 Emphasis is on process, not notation
 Well-understood forms allow logical reasoning
about algorithm behavior
 Can be easily translated into a programming
language

6. Sample Pseudocode
 Task: add two numbers
 Pseudocode:
 Start
 Get two numbers
 Get first number
 Get second number
 Add them
 Print the answer
 End

7. What does a flowchart look like?
 The pseudocode from the previous slide would look
like this as a flowchart:
Start
Get 2 numbers
Add them
Print answer
End

8. What are those funny symbols?
 START/END
 INPUT/OUTPUT
 PROCESS
 DECISION

9. What are those funny symbols?
 START/END
 Used at the beginning
and end of each
flowchart.

10.  INPUT/OUTPUT
 Shows when
information/data comes
into a program or is
printed out.
What are those funny symbols?

11. What are those funny symbols?
 PROCESS
 Used to show
calculations, storing of
data in variables, and
other “processes” that
take place within a
program.
What are those funny symbols?

12. What are those funny symbols?
 DECISION
 Used to show that the
program must decide
whether something
(usually a comparison
between numbers) is
true or false. YES and
NO (or T/F) branches
are usually shown.
What are those funny symbols?
Y
N
X>7?

13. Another Sample:
Calculating Age
 Pseudocode:
 Start
 Get year DOB
 Calculate age = (sysdate-DOB)
 Print age
 If age > 50 print OLD
 End

14. Another Sample:
Calculating Age
 Flowchart
 Start
 Get year born
 Calculate age
 Print age
 If age > 50 print OLD
 End
Get yr
Calc age
Print age
Age>50?OLD Y
N
Start
End

15. Self-Check
 Look at the flowchart section below. If the variable X is
5, what will print (K or 1st)?
X > 5?
YN
Print “1st”Print “K”

16. Self-Check
 Look at the flowchart section below. If the variable X is
5, what will print (K or 1st)?
X > 5?
YN
Print “1st”Print “K”
K will be printed. The answer to the question “Is X greater than 5?”
is NO, since X is equal to (not greater than) 5.

17. Self-Check
 Choose the correct
flowchart symbol for each
of these statements.
 AGE>65?
 Calc. Tax
 START
 Print NAME

18. Self-Check
 Choose the correct
flowchart symbol for each
of these statements.
 AGE>65?
 Calc. Tax
 START
 Print NAME

19. Challenge
 Try to write pseudocode and create a flowchart for a
program that calculates the average of three grades
and prints the average.
 The word GOOD should be printed only if the average
is more than 80.

20. Challenge
 Possible pseudocode
 Start
 Get three grades
 Average them (add all of them / number of grads taken)
 Print Average
 Average>80?
 If Yes, print GOOD
 End

21. Challenge
 Possible flowchart
 Start
 Get three grades
 Average them
 Print Average
 Average>80?
 If Yes, print GOOD
 End
START
END
Get 3 grades
Calc avg
Print avg
Avg>80?GOOD
Y
N

22. Challenge
 Try to write pseudocode and create a flowchart for a
program that calculates the average of three grades
and prints the average.
 The word GOOD should be printed only if the average
is more than 80.

23. Challenge
 Possible pseudocode
 Start
 Get three grades
 Average them
 Print Average
 Average>80?
 If Yes, print GOOD
 End

24. Challenge
 Possible flowchart
 Start
 Get three grades
 Average them
 Print Average
 Average>80?
 If Yes, print GOOD
 End
START
END
Get 3 grades
Calc avg
Print avg
Avg>80?GOOD
Y
N

26.  Algorithm for Computing Average Miles per
Gallon

28.  Write a program to do the task: Print a list of the numbers
from 4 to 9, next to each number, print the square of the
number.