CODEWITHSUNDEEP
c#multithreadingparameterized
Tyler Treat
Tyler Treat

Reputation: 14998

Issue creating a parameterized thread

I'm having problems trying to create a thread with a ParameterizedThreadStart. Here's the code I have now:

public class MyClass
{
    public static void Foo(int x)
    {
        ParameterizedThreadStart p = new ParameterizedThreadStart(Bar); // no overload for Bar matches delegate ParameterizedThreadStart
        Thread myThread = new Thread(p);
        myThread.Start(x);
    }

    private static void Bar(int x)
    {
        // do work
    }
}

I'm not really sure what I'm doing wrong since the examples I found online appear to be doing the same thing.

Upvotes: 11

Views: 8860

Answers (6)

Snowbear
Snowbear

Reputation: 17274

Method Bar should accept object parameter. You should cast to int inside. I would use lambdas here to avoid creating useless method: 

public static void Foo(int x)
{
    ParameterizedThreadStart p = new ParameterizedThreadStart(o => Bar((int)o));
    Thread myThread = new Thread(p);
    myThread.Start(x);
}

private static void Bar(int x)
{
    // do work
}

Upvotes: 3

Vincent Vancalbergh
Vincent Vancalbergh

Reputation: 3327

You need to change Bar to

private static void Bar(object ox)
{
   int x = (int)ox;
   ...
}

The function you pass to ParameterisedThreadStart needs to have 1 single parameter of type Object. Nothing else.

Upvotes: 3

Coincoin
Coincoin

Reputation: 28596

Bar must take an object in parameter, not an int

private static void Bar(object x)
{ 
    // do work
}

Upvotes: 1

toby
toby

Reputation: 902

It is expecting an object argument so you can pass any variable, then you have to cast it to the type you want:

private static void Bar(object o)
{
    int x = (int)o;
    // do work
}

Upvotes: 3

decyclone
decyclone

Reputation: 30830

This is what ParameterizedThreadStart looks like:

public delegate void ParameterizedThreadStart(object obj); // Accepts object

Here is your method:

private static void Bar(int x) // Accepts int

To make this work, change your method to:

private static void Bar(object obj)
{
    int x = (int)obj;
    // todo
}

Upvotes: 7

Dan Tao
Dan Tao

Reputation: 128307

Frustratingly, the ParameterizedThreadStart delegate type has a signature accepting one object parameter.

You'd need to do something like this, basically:

// This will match ParameterizedThreadStart.
private static void Bar(object x)
{
    Bar((int)x);
}

private static void Bar(int x)
{
    // do work
}

Upvotes: 17

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