Lesson 7 : Controlling Program Flow

7.1 Conditional Operators

To control the VB program flow, we can use various conditional operators. Basically, they resemble mathematical operators. Conditional operators are very powerful tools, they let the VB program compare data values and then decide what action to take, whether to execute a program or terminate the program and more. These operators are shown in Table 7.1.

7.2 Logical Operators

In addition to conditional operators, there are a few logical operators which offer added power to the VB programs. There are shown in Table 7.2.

Table 7.1: Conditional Operators



Equal to


More than


Less Than


More than and equal


Less than and equal


Not Equal to

Table 7.2:Logical Operators




Both sides must be true


One side or other must be true


One side or other must be true but not both


Negates truth

* You can also compare strings with the above operators. However, there are certain rules to follows: Upper case letters are less than lowercase letters, "A"<"B"<"C"<"D".......<"Z" and number are less than letters.

7.3 Using If.....Then.....Else Statements with Operators

To effectively control the VB program flow, we shall use If...Then...Else statement together with the conditional operators and logical operators.
The general format for the if...then...else statement is

If conditions Then

VB expressions


VB expressions

End If

* any If..Then..Else statement must end with End If. Sometime it is not necessary to use Else.


Private Sub OK_Click()



If total=firstnum+secondnum And Val(sum.Text)<>0 Then

correct.Visible = True
wrong.Visible = False
correct.Visible = False
wrong.Visible = True
End If

End Sub

*VBTutor lesson 7

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