Discussions

Built-in Functions (MsgBox and InputBox)

A function is similar to a procedure but the main purpose of the function is to accept a certain input from the user and return a value which is passed on to the main program to finish the execution. There are two types of functions, the built-in functions (or internal functions) and the functions created by the programmers

The general format of a function is  FunctionName (arguments) 

The arguments are values that are passed on to the function. In this lesson, you will learn two very basic but useful internal functions of Visual basic , i.e.  the MsgBox( ) and InputBox ( ) functions. 

MsgBox ( ) Function

The objective of MsgBox is to produce a pop-up message box that prompt the user to click on a command button before he /she can continues. This  format 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 Table 10.1 for types of command button displayed. The Title argument will display the title of the message board.

Table 10.1: Style Values
Style Value Named Constant Buttons Displayed
0 vbOkOnly Ok button
1 vbOkCancel Ok and Cancel buttons
2 vbAbortRetryIgnore Abort, Retry and Ignore buttons.
3 vbYesNoCancel Yes, No and Cancel buttons
4 vbYesNo Yes and No buttons
5 vbRetryCancel Retry and Cancel buttons


We can use named constant in place of integers for the second argument to make the programs more readable. In fact, VB6 will automatically shows up a list of names constant  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 10.2 shows the values, the corresponding named constant and buttons. 
 
Table 10.2 : Return Values and Command Buttons

 Value
Named Constant Button Clicked 
1 vbOk Ok button
2 vbCancel Cancel button
3 vbAbort Abort button
4 vbRetry Retry button
5 vbIgnore Ignore button
6 vbYes Yes button
7 vbNo No button


To make the message box looks more sophisticated, you can add an icon besides the message. There are four types of icons available in VB as shown in  Table 10.3


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. The format is  
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 key in.
  • x-position and y-position - The position or the coordinate of the input box. 

Source: vbtutor WEB