Control structures - 1.Branching - 1. IF Statement

    

  Branching statements are used to cause certain actions within a program if a certain condition is met.

·         Syntax

 If <condition > Then statement

     

            If Balance - Check < 0 Then Print "You are overdrawn"

     

Here, if and only if Balance - Check is less than zero, the statement “You are overdrawn” is printed.

    If  Then   End If blocks to allow multiple statements:

      Syntax

IF <condition> then

      statement1

      statement2

      ................

      statementn

end if

eg1:-   Private Sub Command1_Click()

number = Text1.Text

If number Mod 2 = 0 Then

                                    MsgBox ("Even")

End If

End Sub

            If Balance - Check < 0 Then

              Print "You are overdrawn"

              Print "Authorities have been notified"

            End If

      In this case, if Balance - Check is less than zero, two lines of information are printed.

Nested IF

     

eg2     

IF Boolean Expression Then

            Statement1

            Statement2

            Statement2

            ....................

            ....................

            Statementn

Else

IF Boolean Expression Then

                        Statement1

                        Statement2

                        Statement2

                        ....................

                        ....................

                        Statementn

Else

                        Statement1

                        Statement2

                        Statement2

                        ....................

                        ....................

                        Statementn

            End If

End if

Private Sub Command1_Click()

number = Text1.Text

If number Mod 2 = 0 Then

            MsgBox ("Even")

Else

            MsgBox ("odd")

End If

End Sub

If Balance - Check < 0 Then

              Print "You are overdrawn"

              Print "Authorities have been notified"

            Else

              Balance = Balance - Check

            End If

     

Here, the same two lines are printed if you are overdrawn (Balance - Check < 0), but, if you are not overdrawn (Else), your new Balance is computed.

    Or, we can add the ElseIf statement:

     

            If Balance - Check < 0 Then

              Print "You are overdrawn"

              Print "Authorities have been notified"

            ElseIf Balance - Check = 0 Then

              Print "Whew! You barely made it"

              Balance = 0

            Else

              Balance = Balance - Check

            End If

     

Now, one more condition is added.  If your Balance equals the Check amount (ElseIf Balance - Check = 0), a different message appears.

·         In using branching statements, make sure you consider all viable possibilities in the If/Else/End If structure.  Also, be aware that each If and ElseIf in a block is tested sequentially.  The first time an If test is met, the code associated with that condition is executed and the If block is exited.  If a later condition is also True, it will never be considered.

   

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