Invoke Native Methods with DllImport

Added by dholton dholton

Here are some samples:

import System.Runtime.InteropServices

[DllImport("user32.dll")]
def MessageBeep(n as uint) as int:
	pass

def beep():
	MessageBeep(0)

beep()

Actually, a more cross-platform way to make a beep sound is to call Microsoft.VisualBasic.Interaction.Beep() (add a reference to the Microsoft.VisualBasic.dll in the GAC or do "import Microsoft.VisualBasic from Microsoft.VisualBasic"). This is supported in both .NET and Mono.

import System.Runtime.InteropServices

[DllImport("msvcrt.dll")]
def puts (c as string) as int:
	pass

[DllImport("msvcrt.dll")]
def _flushall () as int:
	pass

puts("testing...")
_flushall()

Here is another example with the EntryPoint specified as a named parameter. Useful I guess if you want to use a different name for the dll call.

import System.Runtime.InteropServices

[DllImport("User32.dll", EntryPoint:"MessageBox")]
def msgbox(hwnd as int, msg as string, caption as string, msgtype as int):
	pass

def msgbox(msg as string):
	msgbox(0,msg,"Message",0)
	
msgbox(0, "MessageDialog called", "DllImport Demo", 0)

msgbox("one more time")

For further information, see:

• P/Invoke tutorial.
• Creating a P/Invoke Library