Zhen Jiang Dept. of Computer Science West Chester University West Chester, PA 19383 [email protected] CSC141 Computer Science I
Zhen JiangDept. of Computer Science
West Chester UniversityWest Chester, PA 19383
CSC141 Computer Science I
Introduction T/F selection MC selection
Selection (Decision)
Rolling a dice. Sample execution (click on this link to
try http://www.cis.temple.edu/~jiang/
dice.exe Each button in the above sample has
Selection (Decision)
Win/Lost?Yes
Double themoney Bankrupt
No
Restart
If else statement if (test)
action 1 (statements 1) elseaction 2 (statements 2) //end if
action 3 (statement 3)
Test by boolean expression
Yes
Action 1 Action 2
No
Action 3
Boolean expression in test Simple expression
Format <Value> <relational operators> <Value>
Number value relational operators, Table 3-1, page 111 ==, !=, <, >, <=, >=
!!! Number one error: “(a=2)” instead of “(a==2)” char value (not string!) relational operators
==, != (page 118)
Complex expression &&, ||, ! (Table 3-4, page 135) Truth table
Table 3-6, page 136 Table 3-7, page 139 Table 3-8, page 141
Precedence order, table 3-10, page 142 Number range, page 142-143
Development of a correct decision program Grade.java
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!
Development Process
Exercises 6 and 7, development of a correct decision program
If statement, Code 3-1, page 113 Relational operator ?, page 151 Multiple selection
Nested if, Code 3-4, page 127 If else if, Code 3-5, page 131
Example: letter grade
Comments: Nested if for multiple selection
problemIf
case 1Else
if case 2else…//end of case 2 if
//End of case 1 if
Development of a correct multiple-decision program Letter grade
Exercise 8
Switch Switch([variable]) Case [constant value]: Break (or no break), Code 3-13, 3-14,
page 155-157
Project 2 11 case If-else BMI expression simplification
Last else no if Nested if and multiple if
Avg < 90 && test1 < 90 to attend the final Discount %, ()?