Process.Id Property
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Gets the unique identifier for the associated process.
public:
property int Id { int get(); };
public int Id { get; }
member this.Id : int
Public ReadOnly Property Id As Integer
Property Value
The system-generated unique identifier of the process that is referenced by this Process instance.
Exceptions
The process's Id property has not been set.
-or-
There is no process associated with this Process object.
Examples
The following example demonstrates how to obtain the Id for all running instances of an application. The code creates a new instance of Notepad, lists all the instances of Notepad, and then allows the user to enter the Id number to remove a specific instance.
using System;
using System.Threading;
using System.Security.Permissions;
using System.Security.Principal;
using System.Diagnostics;
class ProcessDemo
{
public static void Main()
{
Process notePad = Process.Start("notepad");
Console.WriteLine("Started notepad process Id = " + notePad.Id);
Console.WriteLine("All instances of notepad:");
// Get Process objects for all running instances on notepad.
Process[] localByName = Process.GetProcessesByName("notepad");
int i = localByName.Length;
while (i > 0)
{
// You can use the process Id to pass to other applications or to
// reference that particular instance of the application.
Console.WriteLine(localByName[i - 1].Id.ToString());
i -= 1;
}
i = localByName.Length;
while (i > 0)
{
Console.WriteLine("Enter a process Id to kill the process");
string id = Console.ReadLine();
if (string.IsNullOrEmpty(id))
break;
try
{
using (Process chosen = Process.GetProcessById(Int32.Parse(id)))
{
if (chosen.ProcessName == "notepad")
{
chosen.Kill();
chosen.WaitForExit();
}
}
}
catch (Exception e)
{
Console.WriteLine("Incorrect entry.");
continue;
}
i -= 1;
}
}
}
open System
open System.Diagnostics
let notePad = Process.Start "notepad"
printfn $"Started notepad process Id = {notePad.Id}"
printfn "All instances of notepad:"
// Get Process objects for all running instances on notepad.
let localByName = Process.GetProcessesByName "notepad"
let mutable i = localByName.Length
while i > 0 do
// You can use the process Id to pass to other applications or to
// reference that particular instance of the application.
printfn $"{localByName.[i - 1].Id}"
i <- i - 1
i <- localByName.Length
while i > 0 do
printfn "Enter a process Id to kill the process"
let id = Console.ReadLine()
if String.IsNullOrEmpty id then
i <- 0
else
try
use chosen = Int32.Parse id |> Process.GetProcessById
if chosen.ProcessName = "notepad" then
chosen.Kill()
chosen.WaitForExit()
i <- i - 1
with e ->
printfn "Incorrect entry."
Imports System.Threading
Imports System.Security.Permissions
Imports System.Security.Principal
Imports System.Diagnostics
Class ProcessDemo
Public Shared Sub Main()
Dim notePad As Process = Process.Start("notepad")
Console.WriteLine("Started notepad process Id = " + notePad.Id.ToString())
Console.WriteLine("All instances of notepad:")
' Get Process objects for all running instances on notepad.
Dim localByName As Process() = Process.GetProcessesByName("notepad")
Dim i As Integer = localByName.Length
While i > 0
' You can use the process Id to pass to other applications or to
' reference that particular instance of the application.
Console.WriteLine(localByName((i - 1)).Id.ToString())
i -= 1
End While
i = localByName.Length
While i > 0
Console.WriteLine("Enter a process Id to kill the process")
Dim id As String = Console.ReadLine()
If id = String.Empty Then
Exit While
End If
Try
Using chosen As Process = Process.GetProcessById(Int32.Parse(id))
If chosen.ProcessName = "notepad" Then
chosen.Kill()
chosen.WaitForExit()
End If
End Using
Catch e As Exception
Console.WriteLine("Incorrect entry.")
GoTo ContinueWhile1
End Try
i -= 1
ContinueWhile1:
End While
End Sub
End Class
Remarks
The process Id is not valid if the associated process is not running. Therefore, you should ensure that the process is running before attempting to retrieve the Id property. Until the process terminates, the process identifier uniquely identifies the process throughout the system.
You can connect a process that is running on a local or remote computer to a new Process instance by passing the process identifier to the GetProcessById method. GetProcessById is a static
method that creates a new component and sets the Id property for the new Process instance automatically.
Process identifiers can be reused by the system. The Id property value is unique only while the associated process is running. After the process has terminated, the system can reuse the Id property value for an unrelated process.
Because the identifier is unique on the system, you can pass it to other threads as an alternative to passing a Process instance. This action can save system resources yet guarantee that the process is correctly identified.