How to determine which version of Windows?

Question

1. How to determine which version of Windows? WinXP, Vista or 7 etc.
2. 32 or 64 bit?

UPD: for .Net 2.0 - 3.5

Solution 1

You're looking for the Environment.OSVersion, Environment.Is64BitProcess, and Environment.Is64BitOperatingSystem properties.

Before .Net 4.0, you can check whether the process is 64-bit by checking whether IntPtr.Size is 8, and you can check whether the OS is 64-bit using this code:

public static bool Is64BitProcess
{
    get { return IntPtr.Size == 8; }
}

public static bool Is64BitOperatingSystem
{
    get
    {
        // Clearly if this is a 64-bit process we must be on a 64-bit OS.
        if (Is64BitProcess)
            return true;
        // Ok, so we are a 32-bit process, but is the OS 64-bit?
        // If we are running under Wow64 than the OS is 64-bit.
        bool isWow64;
        return ModuleContainsFunction("kernel32.dll", "IsWow64Process") && IsWow64Process(GetCurrentProcess(), out isWow64) && isWow64;
    }
}

static bool ModuleContainsFunction(string moduleName, string methodName)
{
    IntPtr hModule = GetModuleHandle(moduleName);
    if (hModule != IntPtr.Zero)
        return GetProcAddress(hModule, methodName) != IntPtr.Zero;
    return false;
}

[DllImport("kernel32.dll", SetLastError=true)]
[return:MarshalAs(UnmanagedType.Bool)]
extern static bool IsWow64Process(IntPtr hProcess, [MarshalAs(UnmanagedType.Bool)] out bool isWow64);
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError=true)]
extern static IntPtr GetCurrentProcess();
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
extern static IntPtr GetModuleHandle(string moduleName);
[DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError=true)]
extern static IntPtr GetProcAddress(IntPtr hModule, string methodName);

Solution 2

Take a look at Environment.OSVersion and Environment.Is64BitOperatingSystem

Solution 3

You could do

System.OperatingSystem osInfo = System.Environment.OSVersion;

Have a look at this.

Comments

[Grant Thomas]

AFAIK, the OperatingSystem type directly doesn't expose a field to determine the bitiness. Some validation against known terms would need to take place, methinks.

[SLaks]

@MrD: Is64BitOperatingSystem

[Grant Thomas]

@Slaks: Ya, just noticed the update - had no idea Environment housed such a property. Nice one. This must be new to .NET4?

[Admin]

My Windows Version is "Microsoft Windows NT 6.1.7600.0". How determine it XP, Vista or 7?

[SLaks]

XP is 5.1, Vista is 6.0, and 7 is 6.1

[Admin]

Which version for Win2003 and Win2008?

[SLaks]

They're the same as XP and Vista.