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ThreadStart Delegate

Represents the method that executes on a Thread.

Namespace:  System.Threading
Assembly:  mscorlib (in mscorlib.dll)

public delegate void ThreadStart()

When a managed thread is created, the method that executes on the thread is represented by a ThreadStart delegate or a ParameterizedThreadStart delegate that is passed to the Thread constructor. The thread does not begin executing until the Thread::Start method is called. Execution begins at the first line of the method represented by the ThreadStart or ParameterizedThreadStart delegate.


Visual Basic and C# users can omit the ThreadStart or ParameterizedThreadStart delegate constructor when creating a thread. In Visual Basic, use the AddressOf operator when passing your method to the Thread constructor; for example, Dim t As New Thread(AddressOf ThreadProc). In C#, simply specify the name of the thread procedure. The compiler selects the correct delegate constructor.



In version 2.0 of the .NET Framework, creating a ThreadStart delegate for a static method in C++ requires only one parameter: the address of the callback method, qualified by the class name. In earlier versions two parameters were required when creating a delegate for a static method: zero (null) and the method address. For an instance method, all versions require two parameters: the instance variable and the method address.

The following code example shows the syntax for creating and using a ThreadStart delegate with an instance method and with a static method.

For another simple example that demonstrates how to create a ThreadStart delegate, see the Thread::Start() method overload. For more information about thread creation, see Creating Threads and Passing Data at Start Time.

using namespace System;
using namespace System::Threading;
ref class Work
   static void DoWork()
      Console::WriteLine( "Static thread procedure." );

   int Data;
   void DoMoreWork()
      Console::WriteLine( "Instance thread procedure. Data={0}", Data );


int main()

   // To start a thread using an instance method for the thread  
   // procedure, specify the object as the first argument of the 
   // ThreadStart constructor. 
   Work^ w = gcnew Work;
   w->Data = 42;
   ThreadStart^ threadDelegate = gcnew ThreadStart( w, &Work::DoMoreWork );
   Thread^ newThread = gcnew Thread( threadDelegate );

   // To start a thread using a static thread procedure, specify 
   // only the address of the procedure. This is a change from  
   // earlier versions of the .NET Framework, which required  
   // two arguments, the first of which was null (0). 
   threadDelegate = gcnew ThreadStart( &Work::DoWork );
   newThread = gcnew Thread( threadDelegate );

/* This code example produces the following output (the order 
   of the lines might vary):
Static thread procedure.
Instance thread procedure. Data=42

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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