Use managed equivalents of Win32 API
A platform invoke method is used to call an unmanaged DLL function and is defined using the System.Runtime.InteropServices.DllImportAttribute attribute, or the Declare keyword in Visual Basic. An incorrectly defined platform invoke method can lead to runtime exceptions because of issues such as a misnamed function, faulty mapping of parameter and return value data types, and incorrect field specifications, such as the calling convention and character set. If available, it is generally simpler and less error prone to call the equivalent managed method than to define and call the unmanaged method directly. Calling a platform invoke method can also lead to additional security issues that need to be addressed.
The following example shows a platform invoke method definition that violates the rule. In addition, the calls to the platform invoke method and the equivalent managed method are shown.
Imports System Imports System.Runtime.InteropServices Imports System.Text Namespace UsageLibrary Class NativeMethods Private Sub New() End Sub ' The following method definitions violate the rule. <DllImport("kernel32.dll", CharSet := CharSet.Unicode, _ SetLastError := True)> _ Friend Shared Function ExpandEnvironmentStrings _ (lpSrc As String, lpDst As StringBuilder, nSize As Integer) _ As Integer End Function Friend Declare Unicode Function ExpandEnvironmentStrings2 _ Lib "kernel32.dll" Alias "ExpandEnvironmentStrings" _ (lpSrc As String, lpDst As StringBuilder, nSize As Integer) _ As Integer End Class Public Class UseNativeMethod Shared Sub Main() Dim environmentVariable As String = "%TEMP%" Dim expandedVariable As New StringBuilder(100) ' Call the unmanaged method. NativeMethods.ExpandEnvironmentStrings( _ environmentVariable, _ expandedVariable, _ expandedVariable.Capacity) ' Call the unmanaged method. NativeMethods.ExpandEnvironmentStrings2( _ environmentVariable, _ expandedVariable, _ expandedVariable.Capacity) ' Call the equivalent managed method. Environment.ExpandEnvironmentVariables(environmentVariable) End Sub End Class End Namespace