VB.NET Language in a Nutshell, Second Edition

Name

Command Function

Class

Microsoft.VisualBasic.Interaction

Syntax

Command(  )

Return Value

A String containing the command-line arguments

Description

Returns the arguments used when launching VB or an application created with VB

Rules at a Glance

• For applications created with VB and compiled into an EXE, Command returns a string containing everything entered after the executable filename.

• If the executable has been launched with no command-line arguments, Command returns a null string.

Programming Tips and Gotchas

• Once you’ve used the Command function to retrieve the command-line arguments, you still have to parse the string it returns. This should be as simple as a call to the Split function, as shown in the following code fragment:

  Dim sCmdLineStr, sCmdLine(  ) As String
  sCmdLineStr = Command(  )
  If Not sCmdLineStr = "" Then
     sCmdLine = Split(Command, " ")
  End If

• Instead of calling the Command function, you may find it easier to use the shared GetCommandLineArgs method of the System.Environment class. It returns a string array whose first element is the program name and whose remaining elements are the command-line arguments. The following code fragment determines whether any command-line arguments are present:

  Dim sArgs() As String = System.Environment.GetCommandLineArgs(  )
  If sArgs.Length > 1 Then
     ' handle the command line arguments
  End If

Example

The following example demonstrates how to parse command-line arguments to set up a series of options in your executable. This example (which ...