Controlling Program Flow – Modules – Creation of EXE files

1. Controlling Program Flow – Modules – Creation of EXE files • In general VB executes its program from top to bottom and left to right. This is called sequence of execution. • If we want to break the sequence of execution, then we will use a statement called Control statement or Decision making statements. • VB language possesses decision making capabilities and supports the following statements known as control or decision making statements. a) Simple IF …THEN .. END IF statement b) IF … THEN .. ELSE… END IF statement c) Nested IF…. THEN … ELSE …END IF statement d) SELECT CASE statement e) GOTO statement 1) SimpleIF … END IFstatement It is one of the conditional control statement. Syntax : IF condition THEN Statement 1; ----- Statement n; END IF Statement x;

2. Meaning : If <condition> is non-zero (true), <statement1 to statement n > are executed. If < condition > is false <statement x > is executed . Example: Write a VB program to find maximum among two numbers Private Sub Command1_Click ( ) Dim a As Integer Dim b As Integer a = Inputbox(“Enter First number “) b = Inputbox(“Enter Second number “) IF a > b THEN MsgBox (“A is biggest “ & a); END IF IF b > a THEN MsgBox (“Bis biggest “ & b); END IF End sub

3. b) IF … THEN … ELSE statement It is one of the conditional control statement. If we are having two conditions then we will use IF .. THEN .. ELSE statement. Syntax : IF condition True block Statement (s); ELSE False block statement (s); END IF Statement x; Meaning : If <condition> is non-zero (true), < True block statement (s) > is executed. If < condition> is false < False block statement (s) > is executed. Example: Write a VB program to find maximum among two numbers Private Sub Command1_Click ( ) Dim a As Integer, b As Integer a = Inputbox(“Enter First number “) b = Inputbox(“Enter Second number “) IF a > b THEN MsgBox (“A is biggest “ & a); ELSE MsgBox (“Bis biggest “ & b); END IF End sub :

4. c) Nested IF … THEN …ELSE statements It is one of the conditional control statement. If we are having more than two conditions then we will use nested IF …THEN .. ELES statements. Syntax :1 IF condition 1 THEN IF condition 2 THEN Statement Block 1; ELSE Statement Block 2; END IF ELSE Statement 3; END IF Statement x; Meaning : If the condition 1 is false, the statement 3 will be executed. If the condition 1 is true, then control goes to test the condition 2, If the condition 2 is true , the statement 1 will be executed otherwise the statement 2 will be executed and then the control is transferred to the statement x.

5. Example: To find maximum among three numbers Private Sub Command1_Click() Dim a As Integer, b As Integer, c As Integer a = InputBox("Enter first") b = InputBox("Enter second") c = InputBox("Enter third") If a > b Then If a > c Then MsgBox ("A is biggest" & a) Else MsgBox ("C is biggest" & c) End If Else If b > c Then MsgBox ("B is biggest" & b) Else MsgBox ("C is biggest" & c) End If End If End Sub

6. Syntax :2 IF condition 1 THEN Statement Block 1; ELSEIF condition 2 THEN Statement Block 2; ELSEIF condition 3 THEN Statement Block 3; ----- ---- ELSEIF condition n-1 THEN Statement Block n-1; ELSE Statement Block n; END IF Statement x;

7. Example :Write a VB program to find the commission for a salesman according to the following conditions. Sales amount Commission <= 10000 5 % of sales > 10000 and <= 30000 10 % of sales > 30000 and <= 50000 15 % of sales > 50000 20 % of sales Private Sub Command1_Click() Rem Declaration part Dim sname as String, pname As String Dim sno as Integer, samt as Integer , bp as Integer Dim com as Double, net as Double Rem Input part sname = InputBox(" Enter Salesman name ") sno = InputBox(" Enter Salesman number ") pname = InputBox(" Enter Product name ") bp = InputBox(" Enter Basic pay ") samt = InputBox(" Enter sales amount ")

8. Rem Calculation Part IF samt <= 10000 THEN com = samt * 5 /100; ELSEIF samt > 10000 AND samt <= 30000 THEN com = samt * 10 /100; ELSEIF samt > 30000 AND samt <= 50000 THEN com = samt * 15 /100; ELSE com = samt * 20 /100; ENDIF namt = samt + com; Rem Output Part print “Salesman name : “ & sname print “Salesman numbe : ” & sno print “Product name : ” & pname print “Basic pay : ” & bp print “Sales amount : ” & samt print “Commission : ” & com print “Net amount : ” & namt End Sub

9. d) Select Case statement • VBhas a built – in multiway decision statement known as a Select Case . • It is an alternative of a complex IF .. ELSE … THEN statement. • In Select Case structure, the condition is evaluated only once at the top of the structure. Syntax : Select Case expression case value-1 block 1 case value-2: block 2 ------ ------ Case Else block n End Select Statement x;

10. Here expression  is an integer expression or character value -1 , value -2 ….  are constants of constant expressions block1, block2… are statement list may contain zero or more statement Example: Write a VB program to find grade of a student. Private Sub Command1_Click() Rem Declaration part Dim grade As String Dim mark As Integer, avg As Integer mark = InputBox(“ Enter the Student mark “)

11. Rem calculation avg = mark / 10; Select Case avg Case 10 Case 9 Case 8 grade = “ Honours ” Case 7 Case 6 grade = “ First Division ” Case 5 grade = “ Second Division ” Case 4 grade = “ Third Division ” Case Else grade = “Fail” End Select print “ Grade = ” & grade End Sub