pinvoke.net: Edit: kernel32.APIGetVersionEx

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Summary: Is used to get OSVERSIONINFOEX, you can try the System.Environment.OSVersion class.

!!!!C# Signature:
 [DllImport("kernel32", SetLastError = true)]
 private static extern bool GetVersionEx(ref OSVERSIONINFOEX osvi);

[StructLayout(LayoutKind.Sequential)]
 private struct OSVERSIONINFOEX
 {
    public uint dwOSVersionInfoSize;
    public uint dwMajorVersion;
    public uint dwMinorVersion;
    public uint dwBuildNumber;
    public uint dwPlatformId;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
    public string szCSDVersion;
    public UInt16 wServicePackMajor;
    public UInt16 wServicePackMinor;
    public UInt16 wSuiteMask;
    public byte wProductType;
    public byte wReserved;
 }
!!!!VB Signature:

Private Declare Function GetVersionEx Lib "kernel32.dll" _
    Alias "GetVersionExA" _
    (ByRef lpVersionInformation As OSVERSIONINFOEX) As Boolean

<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
        Structure OSVERSIONINFOEX
        Public dwOSVersionInfoSize As Integer
        Public dwMajorVersion As Integer
        Public dwMinorVersion As Integer
        Public dwBuildNumber As Integer
        Public dwPlatformId As Integer
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=128)> _
        Public szCSDVersion As String
        Public wServicePackMajor As Integer
        Public wServicePackMinor As Integer
        Public wSuiteMask As Integer
        Public wProductType As Byte
        Public wReserved As Byte
    End Structure 'OSVERSIONINFOEX

'see if the current process is running on Windows XP
    Public Function IsWinXP() As Boolean

'returns True if running Windows XP
        Dim osv As New OSVERSIONINFOEX

osv.dwOSVersionInfoSize = Marshal.SizeOf(osv)

Dim si As New SYSTEM_INFO

If GetVersionEx(osv) = 1 Then

GetSystemInfo(si)

Return (osv.dwMajorVersion = 5 And osv.dwMinorVersion = 2)
        Else
            Return False
        End If
    End Function

'see if the current process is running on Windows Vista 
    Public Function IsWinVista() As Boolean

'returns True if running Windows Vista
        Dim osv As New OSVERSIONINFOEX
        osv.dwOSVersionInfoSize = Marshal.SizeOf(osv)

If GetVersionEx(osv) = 1 Then
            Return (osv.wProductType = VER_NT_WORKSTATION And osv.dwMajorVersion = 6) 
        Else
            Return False
        End If
    End Function

!!!!User-Defined Types:
None.

!!!!Notes:
None.

!!!!Tips & Tricks:
 don't forget to set the dwOSVersionInfoSize

!!!!Sample Code:
 OSVERSIONINFOEX osVersionInfo = new OSVERSIONINFOEX();
 osVersionInfo.dwOSVersionInfoSize = Marshal.SizeOf(osVersionInfo); // don't forget this line, please!
 GetVersionEx(ref osVersionInfo);

!!!!Alternative Managed API:
System.Environment.OSVersion is provided in all .Net versions and has the same information.

'''OperatingSystem''' Class from '''System''' namespace has similar properties and methods

Documentation: APIGetVersionEx@msdn on MSDN