1. CSC530 Data Structure - Decision
Zhen Jiang
Dept. of Computer Science
West Chester University
West Chester, PA 19383

2. Selection (Decision)
Introduction
T/F selection
MC selection

3. Selection (Decision) Rolling a dice.
Sample execution (click on this link to try)
Each button in the above sample has

4. No
Yes
Win/Lost?
Double the
money
Bankrupt
Restart

5. If else statement
if (test)
action 1 (statements 1)
else
action 2 (statements 2)
//end if
action 3 (statement 3)

6. No
Yes
Test by
boolean expression
Action 1
Action 2
Action 3

7. Boolean expression in test
Simple expression
Format
<Value> <relational operators> <Value>
Number value relational operators
==, !=, <, >, <=, >=
!!! Number one error: “(a=2)” instead of “(a==2)”
char value (not string!) relational operators
==, !=

8. Complex expression
&&, ||, !
Truth table
Precedence order
Number range

9. Development of a correct decision program
Grade.java

10. Development Process Identify two exclusive options
Implement each handling in different action parts
Identify the situation (values) for option selection
Make an expression so that all the situation value for option part 1 will lead to the test result (boolean value) true.
Verify all the situation value for option part 2 will lead to the test false, otherwise, revise the above expression!

11. If statement Relational operator ? Multiple selection
Nested if
If else if
Example: letter grade

12. Comments: Nested if for multiple selection problem If case 1 else if…
//end of case 2 if
//End of case 1 if

13. Development of a correct multiple-decision program
Letter grade

15. Switch
Switch([variable])
Case [constant value]:
Break (or no break)