Main, args. Often developers may need to run a VB.NET program as a command-line utility. And in this situation, the program usually must accept command-line arguments.
By specifying a string array argument to Main, the program will automatically receive arguments. We can then loop over the array and act upon its elements.
Example. To begin, the Main method is specified as a Sub, as it does not return a value. It is contained in a Module—the name of the module is not important.
Module Module1
Sub Main(args as String())
' Step 1: print length of array.
Console.WriteLine("Args length is: {0}", args.Length)
' Step 2: loop over each argument.
For Each arg in args
' Step 3: print argument and use Select Case to match it.
Console.WriteLine("Arg is: {0}", arg)
Select Case arg
Case "test"
Console.WriteLine("TEST ARG")
Case "test2"
Console.WriteLine("TEST2 ARG")
Case Else
Console.WriteLine("Unknown")
End Select
Next
End Sub
End Moduledotnet run test test2
Args length is: 2
Arg is: test
TEST ARG
Arg is: test2
TEST2 ARG
Nothing array. In my testing, the args array is never Nothing, even when zero arguments are present. However, it may be worth testing it with IsNothing, depending on where the program will run.
Even though VB.NET is a good choice for programs with Windows Forms user interfaces, it can be used for console programs. And for simple tasks, console programs are an ideal choice.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.