C#: How to get installing programs exactly like in control panel programs and features?

Question 1

Ok gyus, i wrote class that can get installed programs from registry without hotfixes and updates. It is still not exactly like in control panel but almost. I hope this helps anyone else.

public static class InstalledPrograms
{
    const string registry_key = @"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall";

    public static List<string> GetInstalledPrograms()
    {
        var result = new List<string>();
        result.AddRange(GetInstalledProgramsFromRegistry(RegistryView.Registry32));
        result.AddRange(GetInstalledProgramsFromRegistry(RegistryView.Registry64));
        return result;
    } 

    private static IEnumerable<string> GetInstalledProgramsFromRegistry(RegistryView registryView)
    {
        var result = new List<string>();

        using (RegistryKey key = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, registryView).OpenSubKey(registry_key))
        {
            foreach (string subkey_name in key.GetSubKeyNames())
            {
                using (RegistryKey subkey = key.OpenSubKey(subkey_name))
                {
                    if(IsProgramVisible(subkey))
                    {
                        result.Add((string)subkey.GetValue("DisplayName"));
                    }
                }
            }
        }

        return result;
    }

    private static bool IsProgramVisible(RegistryKey subkey)
    {
        var name = (string)subkey.GetValue("DisplayName");
        var releaseType = (string)subkey.GetValue("ReleaseType");
        //var unistallString = (string)subkey.GetValue("UninstallString");
        var systemComponent = subkey.GetValue("SystemComponent");
        var parentName = (string)subkey.GetValue("ParentDisplayName");

        return
            !string.IsNullOrEmpty(name)
            && string.IsNullOrEmpty(releaseType)
            && string.IsNullOrEmpty(parentName)
            && (systemComponent == null);
    }
}

Question 2

MelnikovI's answer is sufficient for most purposes -- I had 144 items in my list vs 143 in Programs and Features. For review, his solution is to hit these registry locations:

HKLM\Software\Microsoft\Windows\CurrentVersion\Uninstall
HKCU\Software\Microsoft\Windows\CurrentVersion\Uninstall
HKLM\Software\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall

To qualify, each subkey MUST have:

The DisplayName REG_SZ value

And MUST NOT have:

The SystemComponent REG_DWORD (non-zero)
The ParentKeyName or ParentDisplayName REG_SZ values
The ReleaseType REG_SZ value

The one addtional enhancement I have found is for Windows Installer entries, defined as:

The key name is a standard GUID string
The WindowsInstaller REG_DWORD is present (and non-zero)

For such entries, you can take the additional step of using the Win32 function MsiGetProductInfoW from msi.dll, and asking for the "VersionString" property for the GUID represented by the key.

If this function returns 1605: ERROR_UNKNOWN_PRODUCT, it means that the entry is not installed according to Windows Installer, and should be excluded from display.

After implementing this minor tweak, my list is now identical to Programs and Features.

Question 3

I took the code that MelnikovI wrote (which was super helpful) and added a couple things. First, it search four places in the registry:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall

HKLM\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall

HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall

HKCU\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall

It also checks to see if there are any subkeys - if not it skips that one.

Lastly, it does a regex to only allow a certain set of characters [^a-zA-Z0-9 .()+-].

I'm only starting at C#, so I didn't know a way to loop through all four reg locations, so I have two loops (one for HKLM and one for HKCU).

public static class InstalledPrograms
    {
      public static List<string> GetInstalledPrograms()
        {
            var result = new List<string>();
            result.AddRange(GetInstalledProgramsFromRegistry(RegistryView.Registry32));
            result.AddRange(GetInstalledProgramsFromRegistry(RegistryView.Registry64));
            result.Sort();
            return result;
        }
        private static string cleanText(string dirtyText)
        {
            Regex rgx = new Regex("[^a-zA-Z0-9 .()+-]");
            string result = rgx.Replace(dirtyText, "");
            return result;
        }
        private static IEnumerable<string> GetInstalledProgramsFromRegistry(RegistryView registryView)
        {
            var result = new List<string>();
            List<string> uninstall = new List<string>();
            uninstall.Add(@"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall");
            uninstall.Add(@"SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall");
            foreach (string registry_key in uninstall)
            {
               using (RegistryKey key = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, registryView).OpenSubKey(registry_key))
               {
                    foreach (string subkey_name in key.GetSubKeyNames())
                    {
                        using (RegistryKey subkey = key.OpenSubKey(subkey_name))
                        {
                            if (IsProgramVisible(subkey))
                            {
                                result.Add(cleanText(subkey.GetValue("DisplayName").ToString()).ToString());
                            }
                        }
                    }
                }
                using (RegistryKey key = RegistryKey.OpenBaseKey(RegistryHive.CurrentUser, registryView).OpenSubKey(registry_key))
                {
                    if (key != null)
                    {
                        foreach (string subkey_name in key.GetSubKeyNames())
                        {
                            using (RegistryKey subkey = key.OpenSubKey(subkey_name))
                            {
                                if (IsProgramVisible(subkey))
                                {
                                    result.Add(cleanText(subkey.GetValue("DisplayName").ToString()).ToString());
                                }
                            }
                        }
                    }
                }
            }

            return result;
        }

If anyone is interested, I compared the results to the PowerShell I've been using and they are the same.

##Get list of Add/Remove programs
if (!([Diagnostics.Process]::GetCurrentProcess().Path -match '\\syswow64\\'))
{
$uninstallPath = "\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\"
$uninstallWow6432Path = "\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\"
@(
if (Test-Path "HKLM:$uninstallWow6432Path" ) { Get-ChildItem "HKLM:$uninstallWow6432Path"}
if (Test-Path "HKLM:$uninstallPath" ) { Get-ChildItem "HKLM:$uninstallPath" }
if (Test-Path "HKCU:$uninstallWow6432Path") { Get-ChildItem "HKCU:$uninstallWow6432Path"}
if (Test-Path "HKCU:$uninstallPath" ) { Get-ChildItem "HKCU:$uninstallPath" }
) |
ForEach-Object { Get-ItemProperty $_.PSPath } |
Where-Object {
$_.DisplayName -and !$_.SystemComponent -and !$_.ReleaseType -and !$_.ParentKeyName -and ($_.UninstallString -or $_.NoRemove)
} |
Sort-Object DisplayName |
Select-Object DisplayName
}
else
{
"You are running 32-bit Powershell on 64-bit system. Please run 64-bit Powershell instead." | Write-Host -ForegroundColor Red
}

Question 4

The SystemComponent registry key discussed in several other answers here is usually a REG_DWORD with possible values of 0 or 1. However, I have seen a couple of instances (such as Microsoft Visio 2010 and Microsoft Project 2010) where SystemComponent is a REG_SZ with no data. Any solution that casts SystemComponent to an int is therefore liable to throw an exception in these situations.