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How To Programmatically Launch the Default Internet Browser

Article ID: 174156 - View products that this article applies to.

This article was previously published under Q174156

SUMMARY

You can use the Windows API to start the default Internet browser on your system. To do so, you must first determine what Internet browser is registered as the default on your system, and then start that application.

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MORE INFORMATION

The following Visual Basic example will launch whatever Internet browser is registered as the default on your system. Obviously, at least one Internet browser must be successfully installed and set up on the system for this to work. Also, since this code is highly dependent on the application-file type associations in the HKEY_CLASSES_ROOT hive of the registry, this can lead to unexpected results and exceptions if the registry is damaged. File types and extensions may also be associated with applications other than the browser. For example, HTM or HTML files may be associated with web development software instead of the browser.

Note that both API functions in the following sample return a value of 32 or less on failure, but the error constants are not included in this article. Full error trapping is recommended for any production use of this technique.

Step-by-Step Example

Start a new project in Visual Basic. Form1 is created by default.
Add a Command button to Form1. Command1 is created by default.

Copy the following code into the Form's module:

       Private Const SW_SHOW = 5       ' Displays Window in its current size
                                      ' and position
      Private Const SW_SHOWNORMAL = 1 ' Restores Window if Minimized or
                                      ' Maximized

      Private Declare Function ShellExecute Lib "shell32.dll" Alias _
         "ShellExecuteA" (ByVal hwnd As Long, ByVal lpOperation As _
         String, ByVal lpFile As String, ByVal lpParameters As String, _
         ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long

      Private Declare Function FindExecutable Lib "shell32.dll" Alias _
         "FindExecutableA" (ByVal lpFile As String, ByVal lpDirectory As _
         String, ByVal lpResult As String) As Long

      Private Sub Command1_Click()
      Dim FileName As String, Dummy As String
      Dim BrowserExec As String * 255
      Dim RetVal As Long
      Dim FileNumber As Integer

      ' First, create a known, temporary HTML file
      BrowserExec = Space(255)
      FileName = "C:\temphtm.HTM"
      FileNumber = FreeFile                    ' Get unused file number
      Open FileName For Output As #FileNumber  ' Create temp HTML file
          Write #FileNumber, "<HTML> <\HTML>"  ' Output text
      Close #FileNumber                        ' Close file
      ' Then find the application associated with it
      RetVal = FindExecutable(FileName, Dummy, BrowserExec)
      BrowserExec = Trim(BrowserExec)
      ' If an application is found, launch it!
      If RetVal <= 32 Or IsEmpty(BrowserExec) Then ' Error
          MsgBox "Could not find associated Browser", vbExclamation, _
            "Browser Not Found"
      Else
          RetVal = ShellExecute(Me.hwnd, "open", BrowserExec, _
            "www.microsoft.com", Dummy, SW_SHOWNORMAL)
          If RetVal <= 32 Then        ' Error
              MsgBox "Web Page not Opened", vbExclamation, "URL Failed"
          End If
      End If
      Kill FileName                   ' delete temp HTML file
      End Sub

Press the F5 key to run the project. Click on Command1 and your default Internet Browser will start.

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REFERENCES

For more information, please Search on the following topics in either the Win32 Programmer's Reference or The Microsoft Developer Network (MSDN) Library CD-ROM: