Using the Win32 API

In this exercise, you will create a message box using both the Win32 API and the inherent Visual Basic function, MsgBox .

* To create a message box using the Win32 API:

1. Start Microsoft Visual Basic and create a new standard EXE project.
2. From the Project menu, select Add Module .
3. In General Declarations , type the following code:

    Declare Function MessageBox Lib "user32" Alias "MessageBoxA"(ByVal hwnd As Long, ByVal lpText As String, ByVal lpCaption As String, ByVal wType As Long) As Long 

4. Add a new command button control to Form1 .
5. In the Click event of Command1 , type the following code:

    MessageBox Me.hwnd, "API MessageBox function", "API", 0 

6. Run the application.
7. Click Command1 .

   The MessageBox Win32 API function has been called directly from Visual Basic code.

* To create a message box in Visual Basic:

1. Start Visual Basic and select Standard EXE .
2. Add a command button control to Form1 .
3. In the Click event of Command2 , enter the following code:

    MsgBox "Visual Basic MsgBox function" 

4. From the Run menu, click Start to run the program.
5. Click Command12 .

   Notice that a message box has been displayed. Visual Basic internally utilizes the Win32 API to call the MessageBox function in the User32.dll library.