CSC115 Introduction to Computer Programming Zhen Jiang Dept. of Computer Science West Chester University West Chester, PA

Table of Contents Structure Selection (Decision) Loop Array and Function

Price is right. Sample execution (click on this link to try)this link Selection (Decision)

Condition Yes Action 1Action 2 No Action 3

Boolean Expression Yes Action 1 If controlled Action 2 else controlled No Action 3 11/21/20155

If block if condition then action 1 (statements 1) else action 2 (statements 2) end if action 3 (statement 3)

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Condition Simple condition Format Number value relational operators =, <>,, = String value relational operators =, <> Complex condition And, or, not Truth table, table 4, p121

Relational operators have lower precedence than math operators. 5 * 7 >= * (7 - 1)‏ 5 * 7 >= * 6 35 >= >= 33 true Relational operators cannot be chained (unlike math operators) 2 <= x <= 10 error! 11/21/201510

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

Multiple selection Nested if block Example: letter grade

Comments: Nested if block for multiple section problem If then case 1 Else if then case 2 else … end if End if

If block, extension without else if condition then action 1 (statements 1) end if action 3 (statement 3)

Dim x as integer, y as integer x = text1.text y=0 if x > 3 then y =1 if x >10 then y = 2 else y = 3 End if Listbox1.Items.Add( y ) Try 2 Dim x as integer, y as integer x = text1.text y=0 if x > 3 then y =1 if x > 10 then y = 2 End if else y = 3 End if Listbox1.Items.Add( y )

Dim x as integer, y as integer x = text1.text y=0 if x > 3 then y =1 if x >10 then y = 2 else y = 3 End if Listbox1.Items.Add( y ) Dim x as integer, y as integer x = text1.text y=0 if x > 3 then y =1 if x > 10 then y = 2 End if else y = 3 End if Listbox1.Items.Add( y )

Select block Select case A constant A variable An expression Is To range Else And and or

Loop Do while Loop do while condition statements loop statements2

Yes statements1Action 2 No Action 3 condition

Yes Statements1 No Statements2 condition

Other loops

Clock

Function and procedure

Array