Zhen Jiang Dept. of Computer Science West Chester University West Chester, PA CSC141 Computer Science I

Introduction T/F selection MC selection Selection (Decision)

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

Win/Lost? Yes Double the money Bankrupt No Restart

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

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

Boolean expression in test Simple expression Format 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

Ex 6: 9/4/20159

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

Ex 7: Ex 8: 9/4/201513

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 problem If case 1 Else if case 2 else … //end of case 2 if //End of case 1 if

Development of a correct multiple- decision program Letter grade

Ex 9

Switch Switch([variable]) Case [constant value]: Break (or no break), Code 3-13, 3-14, page

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 %, ()?