Programmatically detect if Mouse and Keyboard are plugged in

Question

I was wanting to know what is the best way to detect if a mouse or keyboard is plugged in to the computer? I have an application that is mostly used in a touchscreen standalone but I want to know if there is a keyboard plugged in don't fire off pulling up the windows keyboard or a form that contains a numeric keypad. Then change some behavior if the mouse is plugged in against if it isn't.

Answer 1

Using VB.Net, I would use System.Management (don't forget to add this reference in the Project [Menu] -> Add Reference) ManagementObjectSearcher combined with System.Linq to find the solution like this,

Imports System
Imports System.Management
Imports System.Linq

Public Module Module1
    Public Sub Main()
        Console.WriteLine(HasDevice("PointingDevice"))
        Console.WriteLine(HasDevice("Keyboard"))
        Console.ReadKey()
    End Sub

    Public Function HasDevice(strtype As String)
        Dim searcher As New ManagementObjectSearcher("root\CIMV2", "SELECT * FROM Win32_" + strtype)
        Dim result = From mobj In searcher.Get()
                     Select mobj Where mobj("Status").ToString() = 0
        Return Not IsNothing(result)
    End Function    
End Module

Result

You could also hard-coded it to avoid input mistake like TRiNE suggested (though using C#)

Public Function HasPointingDevice()
    Dim searcher As New ManagementObjectSearcher("root\CIMV2", "SELECT * FROM Win32_PointingDevice")
    Dim result = From mobj In searcher.Get()
                 Select mobj Where mobj("Status").ToString() = 0
    Return Not IsNothing(result)
End Function

Public Function HasKeyboard()
    Dim searcher As New ManagementObjectSearcher("root\CIMV2", "SELECT * FROM Win32_Keyboard")
    Dim result = From mobj In searcher.Get()
                 Select mobj Where mobj("Status").ToString() = 0
    Return Not IsNothing(result)
End Function

And call them like this

Public Sub Main()
    Console.WriteLine(HasPointingDevice())
    Console.WriteLine(HasKeyboard())
    Console.ReadKey()
End Sub

They will produce the same result