Calling an API Function From VB.NET

Category:

C#, VB.NET, ASP.NET

Type:

Snippets

Difficulty:

Beginning

Author:

Intelligent Solutions Inc.

Version Compatibility: Visual Basic.NET

More information:

This snippet calls the GetSystemDirectory API function in VB.NET and shows how to use the StringBuilder class to create a string buffer for API functions that require it. See comments within code for more information.

Originally developed for VB.NET Beta 2; verified to work in VB.NET version 1.0 03/17/02.

Instructions: Copy the declarations and code below and paste directly into your VB project.

Declarations:
Put this at the top of your module. 'Required in all cases when calling API functions Imports System.Runtime.InteropServices 'Required in this example and any API function which 'use a string buffer. Provides the StringBuilder class Imports System.Text 'Put these declarations right under the class declaration '(e.g., in a Form, right under Public Class Form1) <DllImport("KERNEL32.DLL", EntryPoint:="GetSystemDirectoryW", _ SetLastError:=True, CharSet:=CharSet.Unicode, _ ExactSpelling:=True, _ CallingConvention:=CallingConvention.StdCall)> _ Public Shared Function GetSystemDirectory(ByVal Buffer _ As StringBuilder, ByVal Size As Integer) As Long ' Leave function empty - DLLImport attribute ' forces calls to GetSystemDirectory to ' be forwarded to GetSystemDirectory in KERNEL32.DLL End Function Public Const MAX_PATH As Integer = 256

Code: