How to find Microsoft Office version installed using C#

In the past, I had a requirement to find the Microsoft Office version installed (Office 2003, Office 2007 etc) along with their bitness (32-bit or 64-bit).  There was no straight forward way to find out the Microsoft Office version.  I searched around the net and came up with a solution from multiple code snippets I found and analyzed.

Here is a working copy that I derived:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
namespace Blog
{
    public class VersionFinder
    {
        [DllImport("kernel32.dll")]
        static extern IntPtr GetCurrentProcess();
        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        static extern IntPtr GetModuleHandle(string moduleName);
        [DllImport("kernel32", CharSet = CharSet.Auto, SetLastError = true)]
        static extern IntPtr GetProcAddress(IntPtr hModule, [MarshalAs(UnmanagedType.LPStr)]string procName);
        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        static extern bool IsWow64Process(IntPtr hProcess, out bool wow64Process);
        [DllImport("Advapi32.dll")]
        static extern uint RegOpenKeyEx(UIntPtr hKey, string lpSubKey, uint ulOptions, int samDesired, out int phkResult);
        [DllImport("Advapi32.dll")]
        static extern uint RegCloseKey(int hKey);
        [DllImport("advapi32.dll", EntryPoint = "RegQueryValueEx")]
        static extern int RegQueryValueEx(int hKey, string lpValueName, int lpReserved, ref uint lpType,
            System.Text.StringBuilder lpData, ref uint lpcbData);
        private static UIntPtr HKEY_LOCAL_MACHINE = new UIntPtr(0x80000002u);
        private static UIntPtr HKEY_CURRENT_USER = new UIntPtr(0x80000001u);
        private Dictionary<string, string> OfficeVersions = new Dictionary<string, string>();
        public VersionFinder()
        {
            OfficeVersions.Add("7.0", "Office97");
            OfficeVersions.Add("8.0", "Office98");
            OfficeVersions.Add("9.0", "Office2000");
            OfficeVersions.Add("10.0", "OfficeXP");
            OfficeVersions.Add("11.0", "Office2003");
            OfficeVersions.Add("12.0", "Office2007");
            OfficeVersions.Add("14.0", "Office2010");
            OfficeVersions.Add("15.0", "Office2013");
        }
        private string GetOfficeVersionNumber()
        {
            string OfficeVersionNo = null;
            bool Is64BitWindows = Is64BitOperatingSystem();
            if (!Is64BitWindows)
            {
                OfficeVersionNo = GetOfficeVersionNumber("SOFTWARE\\Microsoft\\Office\\");
            }
            else
            {
                OfficeVersionNo = GetOfficeVersionNumber("SOFTWARE\\Microsoft\\Office\\");
                if (OfficeVersionNo == null)
                    OfficeVersionNo = GetOfficeVersionNumber("SOFTWARE\\Wow6432Node\\Microsoft\\Office\\");
            }
            return OfficeVersionNo;
        }
        private string GetOfficeVersionNumber(string RegistryPrefix)
        {
            string CurrentOfficeVersionNo = null;
            foreach (string OfficeVersionNo in OfficeVersions.Keys)
            {
                string Path = GetRegKey64(HKEY_LOCAL_MACHINE, RegistryPrefix + OfficeVersionNo + "\\Excel\\InstallRoot", "Path");
                if (Path != null)
                {
                    CurrentOfficeVersionNo = OfficeVersionNo;
                    break;
                }
            }
            return CurrentOfficeVersionNo;
        }
        public string GetOfficeVersion()
        {
            string OfficeVersionNo = GetOfficeVersionNumber();
            string InstalledOfficeVersion = OfficeVersions[OfficeVersionNo];
            bool Is64BitWindows = Is64BitOperatingSystem();
            if (!Is64BitWindows)
            {
                //If windows is 32 bit, then office cannot be 64 bit
                InstalledOfficeVersion += " (32 bit)";
            }
            else
            {
                Nullable<bool> isOffice64Bit = IsOffice64Bit("SOFTWARE\\Microsoft\\Office\\", OfficeVersionNo);
                if (isOffice64Bit == null)
                    isOffice64Bit = IsOffice64Bit("SOFTWARE\\Wow6432Node\\Microsoft\\Office\\", OfficeVersionNo);
                if (isOffice64Bit.HasValue && isOffice64Bit.Value)
                    InstalledOfficeVersion += " (64 bit)";
                else if (isOffice64Bit.HasValue && !isOffice64Bit.Value)
                    InstalledOfficeVersion += " (32 bit)";
                else
                {
                    InstalledOfficeVersion += " (Unknown bit)";
                }
            }
            return InstalledOfficeVersion;
        }
        private bool Is64BitOperatingSystem()
        {
            if (IntPtr.Size == 8)
            {
                //This size indicates that this is 64-bit programs
                //and 64-bit programs can run only on Windows 64
                return true;
            }
            else
            {
                //This size indicates that this is 32-bit programs
                //and 32-bit programs can run only on Windows 32 and 64
                //Detect if current program is 32-bit, but running on Windows 64
                bool flag;
                return ((DoesWin32MethodExist("kernel32.dll", "IsWow64Process") && IsWow64Process(GetCurrentProcess(), out flag)) && flag);
            }
        }
        private Nullable<bool> IsOffice64Bit(string RegistryPrefix, string OfficeVersionNo)
        {
            Nullable<bool> isOffice64Bit = null;
            string Bitness = GetRegKey64(HKEY_LOCAL_MACHINE, RegistryPrefix + OfficeVersionNo + "\\Outlook", "Bitness");
            if (Bitness == "x86")
                isOffice64Bit = false;
            else if ((Bitness == "x64"))
                isOffice64Bit = true;
            return isOffice64Bit;
        }
        private bool DoesWin32MethodExist(string moduleName, string methodName)
        {
            IntPtr moduleHandle = GetModuleHandle(moduleName);
            if (moduleHandle == IntPtr.Zero)
            {
                return false;
            }
            return (GetProcAddress(moduleHandle, methodName) != IntPtr.Zero);
        }
        private string GetRegKey64(UIntPtr inHive, String inKeyName, String inPropertyName)
        {
            int hkey = 0;
            int in32or64key = 0x0100;
            int QueryValue = 0x0001;
            try
            {
                uint lResult = RegOpenKeyEx(HKEY_LOCAL_MACHINE, inKeyName, 0, QueryValue | in32or64key, out hkey);
                if (0 != lResult) return null;
                uint lpType = 0;
                uint lpcbData = 1024;
                StringBuilder AgeBuffer = new StringBuilder(1024);
                RegQueryValueEx(hkey, inPropertyName, 0, ref lpType, AgeBuffer, ref lpcbData);
                string Age = AgeBuffer.ToString();
                return Age;
            }
            finally
            {
                if (0 != hkey) RegCloseKey(hkey);
            }
        }
    }
}
And, you will be invoking the GetOfficeVersion method as below:

static void Main(string[] args)
{
    String OfficeVersion = new VersionFinder().GetOfficeVersion();
    Console.WriteLine("OfficeVersion: " + OfficeVersion);
    Console.ReadLine();
}

Hope, this is useful.