Develop Reference

Delete a file which is used by another process in c#

I am trying to delete one file which was used by certain another process of my Application.
So its giving an Error that file is used by certain another process.
private void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
DirectoryInfo NewDir = new DirectoryInfo(imagefolderpath1);
FileInfo[] files = NewDir.GetFiles("*.jpg");
foreach (var item in files)
{
string strFile = imagefolderpath1 + "\\" + item.ToString();
if (File.Exists(strFile))
{
File.Delete(strFile);
}
}
}
How should i solve this problem can you please help me????

You need to kill the process which is causing this issue by the following code, something like :
string fileName = #"D:\pathname.jpg";//Path to locked file
Process Handletool = new Process();
Handletool.StartInfo.FileName = "handle.exe";
Handletool.StartInfo.Arguments = fileName+" /accepteula";
Handletool.StartInfo.UseShellExecute = false;
Handletool.StartInfo.RedirectStandardOutput = true;
Handletool.Start();
Handletool.WaitForExit();
string outputTool = Handletool.StandardOutput.ReadToEnd();
string matchPattern = #"(?<=\s+pid:\s+)\b(\d+)\b(?=\s+)";
foreach(Match match in Regex.Matches(outputTool, matchPattern))
{
Process.GetProcessById(int.Parse(match.Value)).Kill();
}
u can get Handle.exe from http://technet.microsoft.com/en-us/sysinternals/bb896655.aspx

The file needs to be released by the other program before it can be deleted. You can use Process Explorer to find out what is locking it if you don't know.

you can't access the file used by another process. But if it's not critical for you app to do this later, you can do this in the System.AppDomain.ProcessExit event handler.
just add the file to a centrally managed list and register your cleanup routine like here:
AppDomain.CurrentDomain.ProcessExit += new EventHandler(deleteFilesIfPossibleNow);
in the handler you must still handle exceptions if files are still accessed from another processes.

instead of using _FormClosed you might want to try launching the form from your other code like this:
DirectoryInfo NewDir;
FileInfo[] files;
using (var form = new Form1())
{
var result = form.ShowDialog();
if (result == DialogResult.Close)
{
NewDir = new DirectoryInfo(imagefolderpath1);
files = NewDir.GetFiles("*.jpg");
}
}
foreach(var item in files) {
string strFile = imagefolderpath1 + "\\" + item.toString();
File.Delete(strFile);
}
i wasn't a hundred % sure how your program is meant to work but you can grab information from the forms before they close then close the files they were using after with this kind of method

open file with a running process

I am making an application that can open a custom document. I connected the document extension to the application (using registry), but when I open the document, it is always opened with a new instance of the application.
I want some logic that can open a document running the current process if it exists. I dont mean a single instance. It should be able to run by multiple instances. Like IE or chrome, it should be able to open an HTML file with tab when the process is running, but it can also run a new instance.
How can I do it?

This article contains a good description (images taken from there as well).
The approach uses ThreadPool object with EventWaitHandle object to pass messages (objects) between processes (.Net Remoting).
When the application starts, it uses CreateSingleInstance() to call the existing instance OR register itself as single instance application.
public static bool CreateSingleInstance( string name, EventHandler<InstanceCallbackEventArgs> callback )
{
EventWaitHandle eventWaitHandle = null;
int curSessionId = System.Diagnostics.Process.GetCurrentProcess().SessionId;
name += curSessionId;
string eventName = string.Format( "{0}-{1}", Environment.MachineName, name );
// If there is another instance
InstanceProxy.IsFirstInstance = false;
InstanceProxy.CommandLineArgs = Environment.GetCommandLineArgs();
try
{
//try to open a handle with the eventName
eventWaitHandle = EventWaitHandle.OpenExisting( eventName );
}
catch
{
InstanceProxy.IsFirstInstance = true;
}
if( InstanceProxy.IsFirstInstance )
{
eventWaitHandle = new EventWaitHandle( false, EventResetMode.AutoReset, eventName );
// register wait handle for this instance (process)
ThreadPool.RegisterWaitForSingleObject( eventWaitHandle, WaitOrTimerCallback, callback, Timeout.Infinite, false );
eventWaitHandle.Close();
// register shared type (used to pass data between processes)
RegisterRemoteType( name );
}
else
{
// here will be the code for the second instance/
}
return InstanceProxy.IsFirstInstance;
}
private static void RegisterRemoteType( string uri )
{
// register remote channel (net-pipes)
var serverChannel = new IpcServerChannel( Environment.MachineName + uri );
ChannelServices.RegisterChannel( serverChannel, true );
// register shared type
RemotingConfiguration.RegisterWellKnownServiceType(
typeof( InstanceProxy ), uri, WellKnownObjectMode.Singleton );
// close channel, on process exit
Process process = Process.GetCurrentProcess();
process.Exited += delegate
{
ChannelServices.UnregisterChannel( serverChannel );
};
}
[Serializable]
[System.Security.Permissions.PermissionSet( System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust" )]
internal class InstanceProxy : MarshalByRefObject
{
private static bool firstInstance;
private static string[] arrCommandLineArgs;
public static bool IsFirstInstance
{
get
{
return firstInstance;
}
set
{
firstInstance = value;
}
}
public static string[] CommandLineArgs
{
get
{
return arrCommandLineArgs;
}
set
{
arrCommandLineArgs = value;
}
}
public void SetCommandLineArgs( bool isFirstInstance, string[] commandLineArgs )
{
firstInstance = isFirstInstance;
arrCommandLineArgs = commandLineArgs;
}
}
public class InstanceCallbackEventArgs : EventArgs
{
private bool firstInstance;
private string[] arrCommandLineArgs;
internal InstanceCallbackEventArgs( bool isFirstInstance, string[] commandLineArgs )
{
firstInstance = isFirstInstance;
arrCommandLineArgs = commandLineArgs;
}
public bool IsFirstInstance
{
get
{
return firstInstance;
}
set
{
firstInstance = value;
}
}
public string[] CommandLineArgs
{
get
{
return arrCommandLineArgs;
}
set
{
arrCommandLineArgs = value;
}
}
}

There are many options here, a few them are:
Try use DDE which is ancient history but it is still used by many applications like MS Office. DDE commands are registered on open command for file extension (look HKEY_CLASSES_ROOT\Excel.Sheet.8\shell\Open for example). If application hasn't already been started, it is launched by OS, and DDE command is submitted. If launched, DDE command is submitted to running instance which is registered as a DDE server.
When your process starts try to create an IpcChannel with a predefined name. If your process is launched with file argument, pass file name to running process via IpcChannel. Problem is only one process can create IpcChannel with same name. If that process quits, other processes are left without an open channel.
Every process creates an IpcChannel using process id. When your process starts with a file argument, you enumerate processes where process' path is same as yours, then connect to that process using IpcChannel (where name can be obtained by looking at process id), and then pass filename to it.
Enumerate processes where process' path is same as yours, and send a WM_COPYDATA message containing your filename.

Checking if my Windows application is running

How do I check if my C# Windows application is running ?
I know that I can check the process name but the name can be changed if the exe changes.
Is there any way to have a hash key or something to make my application unique?

public partial class App : System.Windows.Application
{
public bool IsProcessOpen(string name)
{
foreach (Process clsProcess in Process.GetProcesses())
{
if (clsProcess.ProcessName.Contains(name))
{
return true;
}
}
return false;
}
protected override void OnStartup(StartupEventArgs e)
{
// Get Reference to the current Process
Process thisProc = Process.GetCurrentProcess();
if (IsProcessOpen("name of application.exe") == false)
{
//System.Windows.MessageBox.Show("Application not open!");
//System.Windows.Application.Current.Shutdown();
}
else
{
// Check how many total processes have the same name as the current one
if (Process.GetProcessesByName(thisProc.ProcessName).Length > 1)
{
// If ther is more than one, than it is already running.
System.Windows.MessageBox.Show("Application is already running.");
System.Windows.Application.Current.Shutdown();
return;
}
base.OnStartup(e);
}
}

The recommended way is to use a Mutex. You can check out a sample here :
http://www.codeproject.com/KB/cs/singleinstance.aspx
In specific the code:
///
/// check if given exe alread running or not
///
/// returns true if already running
private static bool IsAlreadyRunning()
{
string strLoc = Assembly.GetExecutingAssembly().Location;
FileSystemInfo fileInfo = new FileInfo(strLoc);
string sExeName = fileInfo.Name;
bool bCreatedNew;
Mutex mutex = new Mutex(true, "Global\\"+sExeName, out bCreatedNew);
if (bCreatedNew)
mutex.ReleaseMutex();
return !bCreatedNew;
}

For my WPF application i've defined global app id and use semaphore to handle it.
public partial class App : Application
{
private const string AppId = "c1d3cdb1-51ad-4c3a-bdb2-686f7dd10155";
//Passing name associates this sempahore system wide with this name
private readonly Semaphore instancesAllowed = new Semaphore(1, 1, AppId);
private bool WasRunning { set; get; }
private void OnExit(object sender, ExitEventArgs e)
{
//Decrement the count if app was running
if (this.WasRunning)
{
this.instancesAllowed.Release();
}
}
private void OnStartup(object sender, StartupEventArgs e)
{
//See if application is already running on the system
if (this.instancesAllowed.WaitOne(1000))
{
new MainWindow().Show();
this.WasRunning = true;
return;
}
//Display
MessageBox.Show("An instance is already running");
//Exit out otherwise
this.Shutdown();
}
}

Checkout: What is a good pattern for using a Global Mutex in C#?
// unique id for global mutex - Global prefix means it is global to the machine
const string mutex_id = "Global\\{B1E7934A-F688-417f-8FCB-65C3985E9E27}";
static void Main(string[] args)
{
using (var mutex = new Mutex(false, mutex_id))
{
// edited by Jeremy Wiebe to add example of setting up security for multi-user usage
// edited by 'Marc' to work also on localized systems (don't use just "Everyone")
var allowEveryoneRule = new MutexAccessRule(new SecurityIdentifier(WellKnownSidType.WorldSid, null), MutexRights.FullControl, AccessControlType.Allow);
var securitySettings = new MutexSecurity();
securitySettings.AddAccessRule(allowEveryoneRule);
mutex.SetAccessControl(securitySettings);
//edited by acidzombie24
var hasHandle = false;
try
{
try
{
// note, you may want to time out here instead of waiting forever
//edited by acidzombie24
//mutex.WaitOne(Timeout.Infinite, false);
hasHandle = mutex.WaitOne(5000, false);
if (hasHandle == false) return;//another instance exist
}
catch (AbandonedMutexException)
{
// Log the fact the mutex was abandoned in another process, it will still get aquired
}
// Perform your work here.
}
finally
{
//edit by acidzombie24, added if statemnet
if (hasHandle)
mutex.ReleaseMutex();
}
}
}

you need a way to say that "i am running" from the app,
1) open a WCF ping service
2) write to registry/file on startup and delete on shutdown
3) create a Mutex
... i prefer the WCF part because you may not clean up file/registry correctly and Mutex seems to have its own issues

Mutex and Semaphore didn't work in my case (I tried them as suggested, but it didn't do the trick in the application I developed). The answer abramlimpin provided worked for me, after I made a slight modification.
This is how I got it working finally.
First, I created some helper functions:
public static class Ext
{
private static string AssemblyFileName(this Assembly myAssembly)
{
string strLoc = myAssembly.Location;
FileSystemInfo fileInfo = new FileInfo(strLoc);
string sExeName = fileInfo.Name;
return sExeName;
}
private static int HowManyTimesIsProcessRunning(string name)
{
int count = 0;
name = name.ToLowerInvariant().Trim().Replace(".exe", "");
foreach (Process clsProcess in Process.GetProcesses())
{
var processName = clsProcess.ProcessName.ToLowerInvariant().Trim();
// System.Diagnostics.Debug.WriteLine(processName);
if (processName.Contains(name))
{
count++;
};
};
return count;
}
public static int HowManyTimesIsAssemblyRunning(this Assembly myAssembly)
{
var fileName = AssemblyFileName(myAssembly);
return HowManyTimesIsProcessRunning(fileName);
}
}
Then, I added the following to the main method:
[STAThread]
static void Main()
{
const string appName = "Name of your app";
// Check number of instances running:
// If more than 1 instance, cancel this one.
// Additionally, if it is the 2nd invocation, show a message and exit.
var numberOfAppInstances = Assembly.GetExecutingAssembly().HowManyTimesIsAssemblyRunning();
if (numberOfAppInstances == 2)
{
MessageBox.Show("The application is already running!
+"\nClick OK to close this dialog, then switch to the application by using WIN + TAB keys.",
appName, MessageBoxButtons.OK, MessageBoxIcon.Warning);
};
if (numberOfAppInstances >= 2)
{
return;
};
}
If you invoke the application a 3rd, 4th ... time, it does not show the warning any more and just exits immediately.

I really simplistic way I guess would be, for every exe that is running, you could create/open a file on disk in a known location (c:\temp) with a special name "yourapp.lock" and then just count how many of those there are.
A harder way, would be to open up some inter-process communication, or sockets, so with the process list you could interrogate each process to see if it was your application.

Enter a guid in your assembly data.
Add this guid to the registry.
Enter a reg key where the application read it's own name and add the name as value there.
The other task watcher read the reg key and knows the app name.

you can simply use varialbles and one file to check for running your program.
when open the file contain a value and when program closes changes this value to another one.

How can a Windows Service determine its ServiceName?

I've looked and couldn't find what should be a simple question:
How can a Windows Service determine the ServiceName for which it was started?
I know the installation can hack at the registry and add a command line argument, but logically that seems like it should be unnecessary, hence this question.
I'm hoping to run multiple copies of a single binary more cleanly than the registry hack.
Edit:
This is written in C#. My apps Main() entry point does different things, depending on
command line arguments:
Install or Uninstall the service. The command line can provide a non-default
ServiceName and can change the number of worker threads.
Run as a command-line executable (for debugging),
Run as a "Windows Service". Here, it creates an instance of my ServiceBase-derived
class, then calls System.ServiceProcess.ServiceBase.Run(instance);
Currently, the installation step appends the service name and thread count to the ImagePath in the registry so the app can determine it's ServiceName.

From: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=387024
Here is a WMI solution. Overriding the ServiceBase.ServiceMainCallback() might also work, but this seems to work for me...
protected String GetServiceName()
{
// Calling System.ServiceProcess.ServiceBase::ServiceNamea allways returns
// an empty string,
// see https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=387024
// So we have to do some more work to find out our service name, this only works if
// the process contains a single service, if there are more than one services hosted
// in the process you will have to do something else
int processId = System.Diagnostics.Process.GetCurrentProcess().Id;
String query = "SELECT * FROM Win32_Service where ProcessId = " + processId;
System.Management.ManagementObjectSearcher searcher =
new System.Management.ManagementObjectSearcher(query);
foreach (System.Management.ManagementObject queryObj in searcher.Get()) {
return queryObj["Name"].ToString();
}
throw new Exception("Can not get the ServiceName");
}

ServiceBase.ServiceName property gives the compile-time name of service. If you specify a different name when installing the service, then ServiceName attribute will not give correct name. So, I had to use below code to obtain the service name of my service.
It's an alternative (without using LINQ) to NVRAM's method:
/**
* Returns the service name of currently running windows service.
*/
static String getServiceName()
{
ServiceController[] scServices;
scServices = ServiceController.GetServices();
// Display the list of services currently running on this computer.
int my_pid = System.Diagnostics.Process.GetCurrentProcess().Id;
foreach (ServiceController scTemp in scServices)
{
// Write the service name and the display name
// for each running service.
// Query WMI for additional information about this service.
// Display the start name (LocalSytem, etc) and the service
// description.
ManagementObject wmiService;
wmiService = new ManagementObject("Win32_Service.Name='" + scTemp.ServiceName + "'");
wmiService.Get();
int id = Convert.ToInt32(wmiService["ProcessId"]);
if (id == my_pid)
{
return scTemp.ServiceName;
#if IS_CONSOLE
Console.WriteLine();
Console.WriteLine(" Service : {0}", scTemp.ServiceName);
Console.WriteLine(" Display name: {0}", scTemp.DisplayName);
Console.WriteLine(" Start name: {0}", wmiService["StartName"]);
Console.WriteLine(" Description: {0}", wmiService["Description"]);
Console.WriteLine(" Found.......");
#endif
}
}
return "NotFound";
}
I was incorrectly trying to obtain the name of windows service as first line in main() without first calling ServiceBase.Run(). We must register our executable as service using ServiceBase.Run() before obtaining its name.
Ref.: http://msdn.microsoft.com/en-us/library/hde9d63a.aspx#Y320

Short version with Linq
int processId = System.Diagnostics.Process.GetCurrentProcess().Id;
ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT * FROM Win32_Service where ProcessId = " + processId);
ManagementObjectCollection collection = searcher.Get();
var serviceName = (string)collection.Cast<ManagementBaseObject>().First()["Name"];

By searching for a better solution i tried this:
string serviceName = "myDynamicServiceName";
string serviceBin = "path\\to\\Service.exe";
string configFile = "path\\to\\myConfig.xml";
string credentials = "obj= .\\mytestuser password= test";
string scCommand = string.Format( "sc create {0} start= auto binPath= \"\\\"{1}\\\" -ini={2} -sn={3}\" type= own{4}", serviceName, serviceBin, configFile , serviceName ,credentials );
I passed the servicename and an configuration file to the binpath.
The service was installed by using the SC.exe (i don't use the installutil!)
On the service you can get the Commandline-Arguments
protected override void OnStart(string[] args){
string binpath = new System.IO.FileInfo(System.Reflection.Assembly.GetAssembly(this.GetType()).Location).DirectoryName + "\\";
System.IO.StreamWriter sw = new System.IO.StreamWriter( binpath + "test.log");
sw.WriteLine( binpath );
string[] cmdArgs = System.Environment.GetCommandLineArgs();
foreach (string item in cmdArgs) {
sw.WriteLine(item);
}
sw.Flush();
sw.Dispose();
sw = null;
}

I had a chicken-and-egg problem where I needed to know the service location before completing Service.Run() (Service could be part of a client or server installation, installer named them appropriately, and I needed to detect which it was on startup)
I relied on the registry to get me the name.
public String IdentifySelfFromRegistry()
{
String executionPath = Assembly.GetEntryAssembly().Location;
Microsoft.Win32.RegistryKey services = Microsoft.Win32.Registry.LocalMachine.OpenSubKey(
#"SYSTEM\CurrentControlSet\services");
if (services != null)
{
foreach(String subkey in services.GetSubKeyNames())
{
if (executionPath.Equals(ServicePathFromServiceKey(services.OpenSubKey(subkey))))
return subkey;
}
}
return String.Empty;
}
protected static String ServicePathFromServiceKey(Microsoft.Win32.RegistryKey serviceKey)
{
if (serviceKey != null)
{
String exec = serviceKey.GetValue(ServicePathEntry) as String;
if (exec != null)
return exec.Trim('\"');
}
return String.Empty;
}

The ServiceMain() entry point that every service executable must implement receives the ServiceName as its first input argument.
If you are writing your service using .NET, the ServiceMain() entry point is implemented by .NET for you. The ServiceName is assigned when the service is installed using the ServiceProcess.ServiceBase.ServiceName property. If you are trying to customize a .NET service to support dynamic ServiceName values, I have no clue how to access the actual ServiceName at runtime.

public static bool IsServiceInstalled(string serviceName)
{
// get list of Windows services
ServiceController[] services = ServiceController.GetServices();
// try to find service name
foreach (ServiceController service in services)
{
if (service.ServiceName == serviceName)
return true;
}
return false;
}

What's wrong with this.ServiceName, if you're inside the service.cs?
i.e.:
protected override void OnStart(string[] args)
{
Logger.Info($"{this.ServiceName} started on {Environment.MachineName}...");
}

Get installed applications in a system

How to get the applications installed in the system using c# code?

Iterating through the registry key "SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" seems to give a comprehensive list of installed applications.
Aside from the example below, you can find a similar version to what I've done here.
This is a rough example, you'll probaby want to do something to strip out blank rows like in the 2nd link provided.
string registry_key = #"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall";
using(Microsoft.Win32.RegistryKey key = Registry.LocalMachine.OpenSubKey(registry_key))
{
foreach(string subkey_name in key.GetSubKeyNames())
{
using(RegistryKey subkey = key.OpenSubKey(subkey_name))
{
Console.WriteLine(subkey.GetValue("DisplayName"));
}
}
}
Alternatively, you can use WMI as has been mentioned:
ManagementObjectSearcher mos = new ManagementObjectSearcher("SELECT * FROM Win32_Product");
foreach(ManagementObject mo in mos.Get())
{
Console.WriteLine(mo["Name"]);
}
But this is rather slower to execute, and I've heard it may only list programs installed under "ALLUSERS", though that may be incorrect. It also ignores the Windows components & updates, which may be handy for you.

I wanted to be able to extract a list of apps just as they appear in the start menu. Using the registry, I was getting entries that do not show up in the start menu.
I also wanted to find the exe path and to extract an icon to eventually make a nice looking launcher. Unfortunately, with the registry method this is kind of a hit and miss since my observations are that this information isn't reliably available.
My alternative is based around the shell:AppsFolder which you can access by running explorer.exe shell:appsFolder and which lists all apps, including store apps, currently installed and available through the start menu. The issue is that this is a virtual folder that can't be accessed with System.IO.Directory. Instead, you would have to use native shell32 commands. Fortunately, Microsoft published the Microsoft.WindowsAPICodePack-Shell on Nuget which is a wrapper for the aforementioned commands. Enough said, here's the code:
// GUID taken from https://learn.microsoft.com/en-us/windows/win32/shell/knownfolderid
var FOLDERID_AppsFolder = new Guid("{1e87508d-89c2-42f0-8a7e-645a0f50ca58}");
ShellObject appsFolder = (ShellObject)KnownFolderHelper.FromKnownFolderId(FOLDERID_AppsFolder);
foreach (var app in (IKnownFolder)appsFolder)
{
// The friendly app name
string name = app.Name;
// The ParsingName property is the AppUserModelID
string appUserModelID = app.ParsingName; // or app.Properties.System.AppUserModel.ID
// You can even get the Jumbo icon in one shot
ImageSource icon = app.Thumbnail.ExtraLargeBitmapSource;
}
And that's all there is to it. You can also start the apps using
System.Diagnostics.Process.Start("explorer.exe", #" shell:appsFolder\" + appModelUserID);
This works for regular Win32 apps and UWP store apps. How about them apples.
Since you are interested in listing all installed apps, it is reasonable to expect that you might want to monitor for new apps or uninstalled apps as well, which you can do using the ShellObjectWatcher:
ShellObjectWatcher sow = new ShellObjectWatcher(appsFolder, false);
sow.AllEvents += (s, e) => DoWhatever();
sow.Start();
Edit: One might also be interested in knowing that the AppUserMoedlID mentioned above is the unique ID Windows uses to group windows in the taskbar.
2022: Tested in Windows 11 and still works great. Windows 11 also seems to cache apps that aren't installed per se, portable apps that don't need installing, for example. They appear in the start menu search results and can also be retrieved from shell:appsFolder as well.

I agree that enumerating through the registry key is the best way.
Note, however, that the key given, #"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall", will list all applications in a 32-bit Windows installation, and 64-bit applications in a Windows 64-bit installation.
In order to also see 32-bit applications installed on a Windows 64-bit installation, you would also need to enumeration the key #"SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall".

You can take a look at this article. It makes use of registry to read the list of installed applications.
public void GetInstalledApps()
{
string uninstallKey = #"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall";
using (RegistryKey rk = Registry.LocalMachine.OpenSubKey(uninstallKey))
{
foreach (string skName in rk.GetSubKeyNames())
{
using (RegistryKey sk = rk.OpenSubKey(skName))
{
try
{
lstInstalled.Items.Add(sk.GetValue("DisplayName"));
}
catch (Exception ex)
{ }
}
}
}
}

While the accepted solution works, it is not complete. By far.
If you want to get all the keys, you need to take into consideration 2 more things:
x86 & x64 applications do not have access to the same registry.
Basically x86 cannot normally access x64 registry. And some
applications only register to the x64 registry.
and
some applications actually install into the CurrentUser registry instead of the LocalMachine
With that in mind, I managed to get ALL installed applications using the following code, WITHOUT using WMI
Here is the code:
List<string> installs = new List<string>();
List<string> keys = new List<string>() {
#"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall",
#"SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall"
};
// The RegistryView.Registry64 forces the application to open the registry as x64 even if the application is compiled as x86
FindInstalls(RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64), keys, installs);
FindInstalls(RegistryKey.OpenBaseKey(RegistryHive.CurrentUser, RegistryView.Registry64), keys, installs);
installs = installs.Where(s => !string.IsNullOrWhiteSpace(s)).Distinct().ToList();
installs.Sort(); // The list of ALL installed applications
private void FindInstalls(RegistryKey regKey, List<string> keys, List<string> installed)
{
foreach (string key in keys)
{
using (RegistryKey rk = regKey.OpenSubKey(key))
{
if (rk == null)
{
continue;
}
foreach (string skName in rk.GetSubKeyNames())
{
using (RegistryKey sk = rk.OpenSubKey(skName))
{
try
{
installed.Add(Convert.ToString(sk.GetValue("DisplayName")));
}
catch (Exception ex)
{ }
}
}
}
}
}

it's worth noting that the Win32_Product WMI class represents products as they are installed by Windows Installer. not every application use windows installer
however "SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" represents applications for 32 bit. For 64 bit you also need to traverse "HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall" and since not every software has a 64 bit version the total applications installed are a union of keys on both locations that have "UninstallString" Value with them.
but the best options remains the same .traverse registry keys is a better approach since every application have an entry in registry[including the ones in Windows Installer].however the registry method is insecure as if anyone removes the corresponding key then you will not know the Application entry.On the contrary Altering the HKEY_Classes_ROOT\Installers is more tricky as it is linked with licensing issues such as Microsoft office or other products.
for more robust solution you can always combine registry alternative with the WMI.

string[] registryKeys = new string[] {
#"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall",
#"SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall" };
public class InstalledApp
{
public string DisplayName { get; set; }
public string DisplayIcon { get; set; }
public string Version { get; set; }
public string InstallLocation { get; set; }
}
private void AddInstalledAppToResultView(RegistryHive hive, RegistryView view, string registryKey,Dictionary<string,InstalledApp> resultView)
{
using (var key = RegistryKey.OpenBaseKey(hive, view).OpenSubKey(registryKey))
{
foreach (string subKeyName in key.GetSubKeyNames())
{
using (RegistryKey subkey = key.OpenSubKey(subKeyName))
{
var displayName = subkey.GetValue("DisplayName");
var displayIcon = subkey.GetValue("DisplayIcon");
if (displayName == null || displayIcon == null)
continue;
var app = new InstalledApp
{
DisplayName = (string)displayName,
DisplayIcon = (string)displayIcon,
InstallLocation = (string)subkey.GetValue("InstallLocation"),
Version = (string)subkey.GetValue("DisplayVersion")
};
if(!resultView.ContainsKey(app.DisplayName))
{
resultView.Add(app.DisplayName,app);
}
}
}
}
}
void Main()
{
var result = new Dictionary<string,InstalledApp>();
var view = Environment.Is64BitOperatingSystem ? RegistryView.Registry64 : RegistryView.Registry32;
AddInstalledAppToResultView(RegistryHive.LocalMachine, view, registryKeys[0],result);
AddInstalledAppToResultView(RegistryHive.CurrentUser, view, registryKeys[0],result);
AddInstalledAppToResultView(RegistryHive.LocalMachine, RegistryView.Registry64, registryKeys[1],result);
Console.WriteLine("==============" + result.Count + "=================");
result.Values.ToList().ForEach(item => Console.WriteLine(item));
}

Iterate through "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" keys and check their "DisplayName" values.

Use Windows Installer API!
It allows to make reliable enumeration of all programs. Registry is not reliable, but WMI is heavyweight.

The object for the list:
public class InstalledProgram
{
public string DisplayName { get; set; }
public string Version { get; set; }
public string InstalledDate { get; set; }
public string Publisher { get; set; }
public string UnninstallCommand { get; set; }
public string ModifyPath { get; set; }
}
The call for creating the list:
List<InstalledProgram> installedprograms = new List<InstalledProgram>();
string registry_key = #"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall";
using (RegistryKey key = Registry.LocalMachine.OpenSubKey(registry_key))
{
foreach (string subkey_name in key.GetSubKeyNames())
{
using (RegistryKey subkey = key.OpenSubKey(subkey_name))
{
if (subkey.GetValue("DisplayName") != null)
{
installedprograms.Add(new InstalledProgram
{
DisplayName = (string)subkey.GetValue("DisplayName"),
Version = (string)subkey.GetValue("DisplayVersion"),
InstalledDate = (string)subkey.GetValue("InstallDate"),
Publisher = (string)subkey.GetValue("Publisher"),
UnninstallCommand = (string)subkey.GetValue("UninstallString"),
ModifyPath = (string)subkey.GetValue("ModifyPath")
});
}
}
}
}

As others have pointed out, the accepted answer does not return both x86 and x64 installs. Below is my solution for that. It creates a StringBuilder, appends the registry values to it (with formatting), and writes its output to a text file:
const string FORMAT = "{0,-100} {1,-20} {2,-30} {3,-8}\n";
private void LogInstalledSoftware()
{
var line = string.Format(FORMAT, "DisplayName", "Version", "Publisher", "InstallDate");
line += string.Format(FORMAT, "-----------", "-------", "---------", "-----------");
var sb = new StringBuilder(line, 100000);
ReadRegistryUninstall(ref sb, RegistryView.Registry32);
sb.Append($"\n[64 bit section]\n\n{line}");
ReadRegistryUninstall(ref sb, RegistryView.Registry64);
File.WriteAllText(#"c:\temp\log.txt", sb.ToString());
}
private static void ReadRegistryUninstall(ref StringBuilder sb, RegistryView view)
{
const string REGISTRY_KEY = #"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall";
using var baseKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, view);
using var subKey = baseKey.OpenSubKey(REGISTRY_KEY);
foreach (string subkey_name in subKey.GetSubKeyNames())
{
using RegistryKey key = subKey.OpenSubKey(subkey_name);
if (!string.IsNullOrEmpty(key.GetValue("DisplayName") as string))
{
var line = string.Format(FORMAT,
key.GetValue("DisplayName"),
key.GetValue("DisplayVersion"),
key.GetValue("Publisher"),
key.GetValue("InstallDate"));
sb.Append(line);
}
key.Close();
}
subKey.Close();
baseKey.Close();
}

Your best bet is to use WMI. Specifically the Win32_Product class.

Might I suggest you take a look at WMI (Windows Management Instrumentation).
If you add the System.Management reference to your C# project, you'll gain access to the class `ManagementObjectSearcher', which you will probably find useful.
There are various WMI Classes for Installed Applications, but if it was installed with Windows Installer, then the Win32_Product class is probably best suited to you.
ManagementObjectSearcher s = new ManagementObjectSearcher("SELECT * FROM Win32_Product");

I used Nicks approach - I needed to check whether the Remote Tools for Visual Studio are installed or not, it seems a bit slow, but in a seperate thread this is fine for me. - here my extended code:
private bool isRdInstalled() {
ManagementObjectSearcher p = new ManagementObjectSearcher("SELECT * FROM Win32_Product");
foreach (ManagementObject program in p.Get()) {
if (program != null && program.GetPropertyValue("Name") != null && program.GetPropertyValue("Name").ToString().Contains("Microsoft Visual Studio 2012 Remote Debugger")) {
return true;
}
if (program != null && program.GetPropertyValue("Name") != null) {
Trace.WriteLine(program.GetPropertyValue("Name"));
}
}
return false;
}

My requirement is to check if specific software is installed in my system. This solution works as expected. It might help you. I used a windows application in c# with visual studio 2015.
private void Form1_Load(object sender, EventArgs e)
{
object line;
string softwareinstallpath = string.Empty;
string registry_key = #"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall";
using (var baseKey = Microsoft.Win32.RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64))
{
using (var key = baseKey.OpenSubKey(registry_key))
{
foreach (string subkey_name in key.GetSubKeyNames())
{
using (var subKey = key.OpenSubKey(subkey_name))
{
line = subKey.GetValue("DisplayName");
if (line != null && (line.ToString().ToUpper().Contains("SPARK")))
{
softwareinstallpath = subKey.GetValue("InstallLocation").ToString();
listBox1.Items.Add(subKey.GetValue("InstallLocation"));
break;
}
}
}
}
}
if(softwareinstallpath.Equals(string.Empty))
{
MessageBox.Show("The Mirth connect software not installed in this system.")
}
string targetPath = softwareinstallpath + #"\custom-lib\";
string[] files = System.IO.Directory.GetFiles(#"D:\BaseFiles");
// Copy the files and overwrite destination files if they already exist.
foreach (var item in files)
{
string srcfilepath = item;
string fileName = System.IO.Path.GetFileName(item);
System.IO.File.Copy(srcfilepath, targetPath + fileName, true);
}
return;
}