ThreadStart with parameters

Question

How do you start a thread with parameters in C

User · Answer

I was having issue in the passed parameter. I passed integer from a for loop to the function and displayed it , but it always gave out different results. like (1,2,2,3) (1,2,3,3) (1,1,2,3) etc with ParametrizedThreadStart delegate.

this simple code worked as a charm

Thread thread = new Thread(Work);
thread.Start(Parameter);

private void Work(object param) 
{
 string Parameter = (string)param; 
}

User · Answer

The ParameterizedThreadStart takes one parameter  You can use that to send one parameter  or a custom class containing several properties   Another method is to put the method that you want to start as an instance member in a class along with properties for the parameters that you want to set  Create an instance of the class  set the properties and start the thread specifying the instance and the method  and the method can access the properties

User · Answer

class Program       static void Main string   args                Thread t   new Thread new ParameterizedThreadStart ThreadMethod             t Start  My Parameter               static void ThreadMethod object parameter                   parameter equals to  My Parameter

User · Answer

As has already been mention in various answers here  the Thread class currently  4 7 2  provides several constructors and a Start method with overloads    These relevant constructors for this question are   public Thread ThreadStart start     and   public Thread ParameterizedThreadStart start     which either take a ThreadStart delegate or a ParameterizedThreadStart delegate   The corresponding delegates look like this   public delegate void ThreadStart    public delegate void ParameterizedThreadStart object obj     So as can be seen  the correct constructor to use seems to be the one taking a ParameterizedThreadStart delegate so that some method conform to the specified signature of the delegate can be started by the thread   A simple example for instanciating the Thread class would be  Thread thread   new Thread new ParameterizedThreadStart Work      or just  Thread thread   new Thread Work     The signature of the corresponding method  called Work in this example  looks like this   private void Work object data               What is left is to start the thread  This is done by using either   public void Start      or  public void Start object parameter     While Start   would start the thread and pass null as data to the method  Start      can be used to pass anything into the Work method of the thread   There is however one big problem with this approach  Everything passed into the Work method is cast into an object  That means within the Work method it has to be cast to the original type again like in the following example   public static void Main string   args        Thread thread   new Thread Work        thread Start  I ve got some text        Console ReadLine       private static void Work object data        string message    string data     Wow  this is ugly      Console WriteLine   I  the thread write   message          Casting is something you typically do not want to do   What if someone passes something else which is not a string  As this seems not possible at first  because It is my method  I know what I do or The method is private  how should someone ever be able to pass anything to it   you may possibly end up with exactly that case for various reasons  As some cases may not be a problem  others are  In such cases you will probably end up with an InvalidCastException which you probably will not notice because it simply terminates the thread   As a solution you would expect to get a generic ParameterizedThreadStart delegate like ParameterizedThreadStart lt T gt  where T would be the type of data you want to pass into the Work method  Unfortunately something like this does not exist  yet     There is however a suggested solution to this issue  It involves creating a class which contains both  the data to be passed to the thread as well as the method that represents the worker method like this   public class ThreadWithState       private string message       public ThreadWithState string message                this message   message             public void Work                 Console WriteLine   I  the thread write   this message               With this approach you would start the thread like this   ThreadWithState tws   new ThreadWithState  I ve got some text    Thread thread   new Thread tws Work    thread Start      So in this way you simply avoid casting around and have a typesafe way of providing data to a thread  -

User · Answer

Simple way using lambda like so    Thread t   new Thread      gt  DoSomething  param1    param2     t Start      OR you could even delegate using ThreadStart like so     ThreadStart ts   delegate        bool moreWork   DoWork  param1    param2    param3         if  moreWork                    DoMoreWork  param4    param5              new Thread ts  Start      OR using VS 2019  NET 4 5  even cleaner like so     private void DoSomething int param1  string param2          DO SOMETHING       void ts                 if  param1  gt  0  DoSomethingElse param2   param3              new Thread ts  Start          DO SOMETHING

User · Answer

You can use lambda expressions   private void MyMethod string param1 int param2        do stuff   Thread myNewThread   new Thread      gt  MyMethod  param1  5    myNewThread Start      this is so far the best answer i could find  it s fast and easy

User · Answer

Yep     Thread t   new Thread  new ParameterizedThreadStart myMethod    t Start  myParameterObject

User · Answer

using System  using System Collections Generic  using System Linq  using System Text  using System Threading Tasks  using System Threading   namespace ConsoleApp6       class Program               static void Main string   args                         int x   10              Thread t1  new Thread new ParameterizedThreadStart order1                t1 Start x                Thread t2 new Thread order2               t2 Priority   ThreadPriority Highest              t2 Start                 Console ReadKey               Main          static void  order1 object args                        int x    int args                for  int i   0  i  lt  x  i                                  Console ForegroundColor   ConsoleColor Green                  Console Write i ToString                                            static void order2                         for  int i   100  i  gt  0  i--                                Console ForegroundColor   ConsoleColor Red                  Console Write i ToString

User · Answer

You can use the BackgroundWorker RunWorkerAsync method and pass in your value

User · Answer

using System  using System Collections Generic  using System Linq  using System Text  using System Threading Tasks  using System Threading   namespace ConsoleApp6       class Program               static void Main string   args                         int x   10              Thread t1  new Thread new ParameterizedThreadStart order1                t1 IsBackground   true   i can stope              t1 Start x                Thread t2 new Thread order2               t2 Priority   ThreadPriority Highest              t2 Start                 Console ReadKey               Main          static void  order1 object args                        int x    int args                    for  int i   0  i  lt  x  i                                  Console ForegroundColor   ConsoleColor Green                  Console Write i ToString                                            static void order2                         for  int i   100  i  gt  0  i--                                Console ForegroundColor   ConsoleColor Red                  Console Write i ToString                                   enter code here

User · Answer

One of the 2 overloads of the Thread constructor takse a ParameterizedThreadStart delegate which allows you to pass a single parameter to the start method   Unfortunately though it only allows for a single parameter and it does so in an unsafe way because it passes it as object   I find it s much easier to use a lambda expression to capture the relevant parameters and pass them in a strongly typed fashion     Try the following  public Thread StartTheThread SomeType param1  SomeOtherType param2      var t   new Thread      gt  RealStart param1  param2      t Start      return t     private static void RealStart SomeType param1  SomeOtherType param2

User · Answer

I propose using Task lt T gt instead of Thread  it allows multiple parameters and executes really fine   Here is a working example       public static void Main                 List lt Task gt  tasks   new List lt Task gt              Console WriteLine  Awaiting threads to finished                string par1    foo           string par2    boo           int par3   3           for  int i   0  i  lt  1000  i                          tasks Add Task Run      gt  Calculate par1  par2  par3                         Task WaitAll tasks ToArray              Console WriteLine  All threads finished                static bool Calculate1 string par1  string par2  int par3                lock  locker                                          return true                          if need to lock  use this      private static Object  locker   new Object          static bool Calculate2 string par1  string par2  int par3                lock  locker                                          return true

User · Answer

Thread thread   new Thread Work   thread Start Parameter    private void Work object param        string Parameter    string param      The parameter type must be an object   EDIT   While this answer isn t incorrect I do recommend against this approach  Using a lambda expression is much easier to read and doesn t require type casting  See here  https   stackoverflow com a 1195915 52551

User · Answer

You could use a ParametrizedThreadStart delegate   string parameter    Hello world    Thread t   new Thread new ParameterizedThreadStart MyMethod    t Start parameter

[c#] ThreadStart with parameters

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