can someone tell me how i can capture a running process in c# using the process class if i already know the handle?
Id rather not have not have to enumerate the getrunning processes method either. pInvoke is ok if possible.
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5 Answers
In plain C#, it looks like you have to loop through them all:
// IntPtr myHandle = ... Process myProcess = Process.GetProcesses().Single( p => p.Id != 0 && p.Handle == myHandle); The above example intentionally fails if the handle isn't found. Otherwise, you could of course use SingleOrDefault. Apparently, it doesn't like you requesting the handle of process ID 0, hence the extra condition.
Using the WINAPI, you can use GetProcessId. I couldn't find it on pinvoke.net, but this should do:
[DllImport("kernel32.dll")] static extern int GetProcessId(IntPtr handle); (signature uses a DWORD, but process IDs are represented by ints in the .NET BCL)
It seems a bit odd that you'd have a handle, but not a process ID however. Process handles are acquired by calling OpenProcess, which takes a process ID.
4 Comments
Grant
i get an access denied message (win32 exception)?
Thorarin
Fixed, but perhaps you should use the WINAPI instead then. That is what you preferred in the first place :)
bh_earth0
process.handle gives access denied but. process.MainWindowHandle runs error free
Latency
Bad -1... MainWindowHandle is for something completely different.
using System.Diagnostics; class ProcessHandler { public static Process FindProcess( IntPtr yourHandle ) { foreach (Process p in Process.GetProcesses()) { if (p.Handle == yourHandle) { return p; } } return null; } } 
Comments
There seems to be no simple way to do this by the .Net API. The question is, where you got that handle from? If by the same way you can get access to the processes ID, you could use:
Process.GetProcessById (int iD)
4 Comments
Thorarin
Getting it by ID would certainly be better/easier, but it's possible by handle. See the other answers.
Grant
an API exposes the HWND but not the ID
Frank Bollack
The question remains, where the handle comes from. If a win32 API is used, maybe another API call should be issued to obtain the process ID from the handle. Another issue is, that handles are only valid within the same process, IDs are system wide
Thorarin
Yeah, I agree that having a handle, but not an ID is very odd.
I'm using these methods for long time:
public static Process FindProcess(IntPtr handle) => FindProcess(p => p.Handle == handle); public static Process FindProcess(int id) => FindProcess(p => p.Id == id); public static Process FindProcess(string title) => FindProcess(p=> p.MainWindowTitle == title); public static Process FindProcess(Func<Process,bool> comparer) { foreach (Process p in Process.GetProcesses()) if (comparer(p)) return p; return null; } Enjoy...
Comments
You could use the GetWindowThreadProcessId WinAPI call
http://www.pinvoke.net/default.aspx/user32/GetWindowThreadProcessId.html
To get the Process Id - then get a Process object using that.....
But why don't you want to enumerate the ids of the running processes?
1 Comment
Thorarin
That one takes a window handle. He has a process handle. The WINAPI
GetProcessId is what he needs.