How to pass parameters to ThreadStart method in Thread

Question

How to pass parameters to Thread ThreadStart   method in C    Suppose I have method called  download   public void download string filename           download code     Now I have created one thread in the main method   Thread thread   new Thread new ThreadStart download filename         error method type expected    How can I pass parameters to ThreadStart with target method with parameters

User · Answer

I would recommend you to have another class called File.

public class File
{
   private string filename;

   public File(string filename)
   {
      this.filename= filename;
   }

   public void download()
   {
       // download code using filename
   }
}

And in your thread creation code, you instantiate a new file:

string filename = "my_file_name";

myFile = new File(filename);

ThreadStart threadDelegate = new ThreadStart(myFile.download);

Thread newThread = new Thread(threadDelegate);

User · Answer

Look at this example   public void RunWorker         Thread newThread   new Thread WorkerMethod       newThread Start new Parameter        public void WorkerMethod object parameterObj        var parameter    Parameter parameterObj         do your job      You are first creating a thread by passing delegate to worker method and then starts it with a Thread Start method which takes your object as parameter   So in your case you should use it like this       Thread thread   new Thread download       thread Start filename     But your  download  method still needs to take object  not string as a parameter  You can cast it to string in your method body

User · Answer

You can encapsulate the thread function download  and the needed parameter s  filename  in a class and use the ThreadStart delegate to execute the thread function   public class Download       string  filename       Download string filename                filename   filename             public void download string filename                 download code          Download   new Download filename   Thread thread   new Thread new ThreadStart Download download

User · Answer

How about this   or is it ok to use like this    var test    Hello   new Thread new ThreadStart      gt        try                 Staff to do         Console WriteLine test             catch  Exception ex                throw            Start

User · Answer

The simplest is just  string filename       Thread thread   new Thread      gt  download filename    thread Start      The advantage s  of this  over ParameterizedThreadStart  is that you can pass multiple parameters  and you get compile-time checking without needing to cast from object all the time

User · Answer

here is the perfect way     private void func trd String sender         try               imgh LoadImages R Randomiz this   01   groupBox  randomizerB Value      normal code          ThreadStart ts   delegate                       ExecuteInForeground sender                       Thread nt   new Thread ts           nt IsBackground   true           nt Start               catch  Exception                  private void ExecuteInForeground string name           whatever ur function     MessageBox Show name

User · Answer

In Additional      Thread thread   new Thread delegate     download i           thread Start

User · Answer

According to your question        How to pass parameters to Thread ThreadStart   method in C        and the error you encountered  you would have to correct your code from   Thread thread   new Thread new ThreadStart download filename      to   Thread thread   new Thread new ThreadStart download    thread Start filename      However  the question is more complex as it seems at first   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

You could also delegate like so     ThreadStart ts   delegate         bool moreWork   DoWork  param1    param2    param3          if  moreWork                     DoMoreWork  param1    param2               new Thread ts  Start

User · Answer

You want to use the ParameterizedThreadStart delegate for thread methods that take parameters   Or none at all actually  and let the Thread constructor infer    Example usage   var thread   new Thread new ParameterizedThreadStart download      var thread   new Thread download      equivalent  thread Start filename

[c#] How to pass parameters to ThreadStart method in Thread?

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