CONTROL STRUCTURE IN VB

BSC 3 YEAR AND CS

1. control structure in visual basic P G D C A - 2 ND S e m VIDYA CLASSES SESSION:-2023-24

2. I N D E X INTRODUCTION TO CONTROL STRUCTURE TYPE OF CONTROL STRUCTURE a) Decision –making statement b) Looping statement Introduction to Decision –making statement Type of Decision –making statement:- Simple if statement If else statement Nested if statement Select case statement Introduction to Looping statement Type of Looping statement:- While wend loop Do while loop Do untill loop Do loop until For next loop For each... next loop

3. Introduction to Control Structure Control Structure are used to control the flow of program’s execution. By default control structure in a program are executed sequentially. There are two types of control structure:- Decision-making Statement Looping Statement0

4. Decision - making Statement There are four types of decision making statement :- ( 1 ) Simple if statement ( 2 ) If-else statement ( 3 ) Nested if statement ( 4 ) Select case statement

5. Simple if statement There is only one condition in the program, then simple if statement is used.It has only the true block of the statement. Syntax:- If(Condition) then Statement block   End If Example:- If(average>40 ) then MsgBox”Passed ” End If

6. If-else Statement The if else statement works like that of simple if statement. With the difference that if you want to execute the false block differently then if else statement is used.In this type of statement you can have one block corresponding to the true condition and the other block corresponding to the false condition. Syntex :- if(Condition ) then Statement block-1 Else Statement block-2 End If Example :- If(average>40 ) then MsgBox “Passed’ Else MsgBox “Failed” End If

7. Nested If statement If you have more then two condition to be tested then another if statement is used in else part of the if statement it is called nesting.     Syntex ;- If(Condition-1 ) then Statement block-1 Else If(Condition-2 ) then Statement block-2 Else If(Condition-3 ) then Statement block-3 - - Else Satement block-n End If End If End If End sub

8. Dim average As Integer average = Val(Text1.Text) If (average > 75) Then printf = "A" Else If (average > 65) Then printf = "B" Else If (average > 55) Then printf = "C" Else If (average > 45) Then printf = "S" Else printf = "F" End If End If End If End If End Sub Example:-

9. Select Case Statement The select case statement is used as an alternative of if then else for selectively Executing one block of statement from among multiple block of statement. Syntex :- Select case Expression Case Expression-1 Statement block-1 Case Expression-2 Statement block-2 - - - Case Else Statement block-n End select Conti....2...

10. Example:- days = Val(Text1.text) If Val(Text1.text) = 1 Then MsgBox "Sunday" Else If Val(Text1.text) = 2 Then MsgBox "Monday" Else If Val(Text1.text) = 3 Then MsgBox "Tuesday" Else If Val(Text1.text) = 4 Then MsgBox "Wednesday" Else If Val(Text1.text) = 5 Then MsgBox "Thursday" Else If Val(Text1.text) = 6 Then MsgBox "Friday" Else If Val(Text1.text) = 7 Then MsgBox "Saturday" Else MsgBox "not weakday " End If End If End If End If End If End If

11. Looping Satetment There are six type of looping statement in visual basic:- (1)While wend loop (2)Do while loop (3)Do untill loop (4)Do loop until (5)For next loop (6)For each... next loop

12. While Wend Loop While wend loop:- While wend loop execute a block of statement while condition is true. Syntex :- While(Condition ) then Statement block Wend Example:- Dim num as Integer Num=0 While(num <=10) Print num Num=num+1 Wend

13. Do while loop Do while loop is exit control loop . Do while works with comparison expression just as the if statement does.     Syntex : - Do while(Condition) then Statement block Loop Example:- Dim i As Integer i =0 Do while( i <10) Print i i =i+1 loop

14. Do until loop Do while loop continues executing the body of the loop as long as the comparision test is true.But do until loop executes the body of the loop as long as the comparision test is false.   Syntex :- Do until (Condition) Statement block Loop Example:- Dim i As Integer i =0 Do until ( i >10) Print i i =i+1 loop

15. Do loop until The loop continues until the loop until statement. The comparision test appears at the bottom of the loop. Hence, the body of the loop always executes atleast once.The body of the loop executes more than once as long as the comparision test stayes false.   Syntex :- Do Statement block Loop until (Condition) Example :- Dim i As Integer i =0 Do Print i i =i+1 loop until ( i >10)

16. For Next loop The for loop repeats for a specific number of times.Hence,for is a Keyword, counter is a variable name & value1,value2 are integer values. The block of statement should be a valid VB statement. Syntex :- For counter=value1 To value2 Statement block Next Counter Example:- For i =1 to 10 Print i Next i

17. For Each.....Next loop For each...next loop repeats a group of statement for each element in a collection of objects or in an array instead of repeating the statement a specified number of time.(Collection can be of objects or arrays)   Syntex :- For Each object/array VB statement Next   Example:- For each element in group VB statement Next element                  

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