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A function is similar to a normal procedure but the main purpose of
the function is to accept a certain input and return a value which is
passed on to the main program to finish the execution. There are two
types of functions in Visual Basic 2010, the built-in functions (or
internal functions) and the functions created by the programmers.
The general syntax of a function is
FunctionName (arguments)
The arguments are values that are passed on to the function.In this lesson, we are going to learn two very basic but useful internal functions of Visual Basic 2010 , i.e. the MsgBox( ) and InputBox ( ) functions.
12.1 MsgBox ( ) Function
The objective of MsgBox is to produce a pop-up message box and prompts the user to click on a command button before he or she can continues. This syntax is as follows:
yourMsg=MsgBox(Prompt, Style Value, Title)
The first argument, Prompt, will display the message in the message box. The Style Value will determine what type of command buttons appear on the message box, please refer to Table 12.1 for types of command button displayed. The Title argument will display the title of the message board.
We can use named constants in place of integers for the second
argument to make the programs more readable. In fact, Visual Basic 2010
will automatically shows up a list of named constants where you can
select one of them.
example: yourMsg=MsgBox( “Click OK to Proceed”, 1, “Startup Menu”)
and yourMsg=Msg(“Click OK to Proceed”. vbOkCancel,”Startup Menu”)
are the same.
yourMsg is a variable that holds values that are returned by the MsgBox ( ) function. The values are determined by the type of buttons being clicked by the users. It has to be declared as Integer data type in the procedure or in the general declaration section. Table 12.2 shows the values, the corresponding named constant and buttons.
Example 12.1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim testmsg As Integer
testmsg = MsgBox(“Click to test”, 1, “Test message”)
If testmsg = 1 Then
MessageBox.Show(“You have clicked the OK button”)
Else
MessageBox.Show(“You have clicked the Cancel button”)
End If
End Sub
To make the message box looks more sophisticated, you can add an icon besides the message. There are four types of icons available in Visual Basic 2010 as shown in Table 12.3
Example 12.2
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim testMsg As Integer
testMsg = MsgBox(“Click to Test”, vbYesNoCancel + vbExclamation, “Test Message”)
If testMsg = 6 Then
MessageBox.Show(“You have clicked the yes button”)
ElseIf testMsg = 7 Then
MessageBox.Show(“You have clicked the NO button”)
Else
MessageBox.Show(“You have clicked the Cancel button”)
End If
End Sub
12.2 The InputBox( ) Function
An InputBox( ) function will display a message box where the user can enter a value or a message in the form of text. In VB2005, you can use the following format:
myMessage=InputBox(Prompt, Title, default_text, x-position, y-position)
myMessage is a variant data type but typically it is declared as string, which accept the message input by the users. The arguments are explained as follows:
Prompt – The message displayed normally as a question asked.
Title – The title of the Input Box.
default-text – The default text that appears in the input field where users can use it as his intended input or he may change to the message he wish to enter.
x-position and y-position – the position or tthe coordinates of the input box.
However, the format won’t work in Visual Basic 2010 because InputBox is considered a namespace. So, you need to key in the full reference to the Inputbox namespace, which is
Microsoft.VisualBasic.InputBox(Prompt, Title, default_text, x-position, y-position)
The parameters remain the same.
Example 12.3
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim userMsg As String
userMsg = Microsoft.VisualBasic.InputBox(“What is your message?”, “Message Entry Form”, “Enter your messge here”, 500, 700)
If userMsg <> “” Then
MessageBox.Show(userMsg)
Else
MessageBox.Show(“No Message”)
End If
End Sub
The inputbox will appear as shown in the figure below when you press the command button
The general syntax of a function is
FunctionName (arguments)
The arguments are values that are passed on to the function.In this lesson, we are going to learn two very basic but useful internal functions of Visual Basic 2010 , i.e. the MsgBox( ) and InputBox ( ) functions.
12.1 MsgBox ( ) Function
The objective of MsgBox is to produce a pop-up message box and prompts the user to click on a command button before he or she can continues. This syntax is as follows:
yourMsg=MsgBox(Prompt, Style Value, Title)
The first argument, Prompt, will display the message in the message box. The Style Value will determine what type of command buttons appear on the message box, please refer to Table 12.1 for types of command button displayed. The Title argument will display the title of the message board.
example: yourMsg=MsgBox( “Click OK to Proceed”, 1, “Startup Menu”)
and yourMsg=Msg(“Click OK to Proceed”. vbOkCancel,”Startup Menu”)
are the same.
yourMsg is a variable that holds values that are returned by the MsgBox ( ) function. The values are determined by the type of buttons being clicked by the users. It has to be declared as Integer data type in the procedure or in the general declaration section. Table 12.2 shows the values, the corresponding named constant and buttons.
Example 12.1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim testmsg As Integer
testmsg = MsgBox(“Click to test”, 1, “Test message”)
If testmsg = 1 Then
MessageBox.Show(“You have clicked the OK button”)
Else
MessageBox.Show(“You have clicked the Cancel button”)
End If
End Sub
To make the message box looks more sophisticated, you can add an icon besides the message. There are four types of icons available in Visual Basic 2010 as shown in Table 12.3
Example 12.2
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim testMsg As Integer
testMsg = MsgBox(“Click to Test”, vbYesNoCancel + vbExclamation, “Test Message”)
If testMsg = 6 Then
MessageBox.Show(“You have clicked the yes button”)
ElseIf testMsg = 7 Then
MessageBox.Show(“You have clicked the NO button”)
Else
MessageBox.Show(“You have clicked the Cancel button”)
End If
End Sub
The first argument, Prompt, will display the message
An InputBox( ) function will display a message box where the user can enter a value or a message in the form of text. In VB2005, you can use the following format:
myMessage=InputBox(Prompt, Title, default_text, x-position, y-position)
myMessage is a variant data type but typically it is declared as string, which accept the message input by the users. The arguments are explained as follows:
Prompt – The message displayed normally as a question asked.
Title – The title of the Input Box.
default-text – The default text that appears in the input field where users can use it as his intended input or he may change to the message he wish to enter.
x-position and y-position – the position or tthe coordinates of the input box.
However, the format won’t work in Visual Basic 2010 because InputBox is considered a namespace. So, you need to key in the full reference to the Inputbox namespace, which is
Microsoft.VisualBasic.InputBox(Prompt, Title, default_text, x-position, y-position)
The parameters remain the same.
Example 12.3
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim userMsg As String
userMsg = Microsoft.VisualBasic.InputBox(“What is your message?”, “Message Entry Form”, “Enter your messge here”, 500, 700)
If userMsg <> “” Then
MessageBox.Show(userMsg)
Else
MessageBox.Show(“No Message”)
End If
End Sub
The inputbox will appear as shown in the figure below when you press the command button
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