In the previous article, you have learned about the if-then-else statements and how you can build a program in VB 6 that work on conditions. The problem with if-then-else structure is that it is very difficult to keep a track of all codes.
The Select-Case is a VB 6 feature that allows to select a case when the condition is met and execute a code. It is a more simplified version of if-then-else statements.
The syntax for Select-Case is given below.
Select Case expression Case 1: some expression; Case 2: some expression; Case 3: some expression; Case 4 To 8: some expression; Case Is <= Total: some expression; Case Else: some default expression; End Select
Select Case ‘expression‘ – Here the Select Case wants a variable or an expression to check if any Case match with it. If there is a match then execute codes under that case.
Case ‘value’ – A case has a number or expression that evaluates to a number. The code under case is executed when the
Select Case condition is met.and its value match with the
End Select – This terminates the
Select Case block.
Each of the case has a value associated with it. It may be in the form of number, or an expression.Let us see few examples below:
Case with number
Case 4: //Case with number and a colon
Case with range of values (expression)
Case 4 To 10: // Gives option to choose number between 4 and 10
Case with logic (expression)
Case Is >= 20: //Case condition evaluates to true and code gets executed
When the case does not match, the last case is Case Else which executes the default statement.
Example Program: Calculator
Private Sub Command1_Click() Dim physics_mark As Integer, maths_mark As Integer Dim english_mark As Integer, average As Integer Dim result As String physics_mark = Val(Text3.Text) maths_mark = Val(Text2.Text) english_mark = Val(Text1.Text) average = (physics_mark + maths_mark + english_mark) / 3 Select Case average Case Is <= 50: Text4.Text = "You Passed" Case Is <= 70: Text4.Text = "Good Marks" Case Is <= 90: Text4.Text = "Top Student" Case Is < 100: Text4.Text = "Exceptional" Case Else Text4.Text = "Sorry! You Failed" End Select End Sub
In the above program, students enter marks for 3 subjects –
English, Mathematics, and Physics. The average of the marks is computed and using
Select-Case the appropriate result is displayed.