CODEWITHSUNDEEP
c#.netmultithreading
Suisse
Suisse

Reputation: 3613

How can I make an async call with System.Threading.Tasks.Task on a function with 2 parameters? In .Net

Given function:

private static int Add(int x, int y)
{
    Console.WriteLine("Add() invoked on thread {0}.",
        Thread.CurrentThread.ManagedThreadId);
    Thread.Sleep(500);
    return x + y;
}

I tried this:

Task<int> t = new Task<int>(x, y => Add(x, y), 5, 6); // 5+6
t.Start();
t.Wait();

// Get the result (the Result property internally calls Wait) 
Console.WriteLine("The sum is: " + t.Result);

It cant be compiled, obviously. How do I do this correctly?

Upvotes: 1

Views: 3069

Answers (2)

user586399
user586399

Reputation: 

Task<int> t = new Task<int>(x, y => Add(x, y), 5, 6); // 5+6

What are you trying to do is to define a Task that takes parameters, and passes these parameters to its inner code.

You can use the overload which takes an object parameter to pass values, like this:

Task<int>.Factory.StartNew(obj => {
            var arr = obj as int[];
            return arr[0] + arr[1];
}, new[] { 5, 4 });

Upvotes: 0

Charles Mager
Charles Mager

Reputation: 26213

First, I'd use Task.Run instead of explicitly creating a new Task. Then I'd await the result rather than blocking until it is completed. This will require the enclosing method to be marked async - you can read more about async/await in this blog post. I'd suggest reading many more on that blog.

You can capture your arguments as part of the lambda expression. This part is the reason why your current code doesn't compile. This is generally more useful than the Action<object> overload in the Task constructor. The end result:

private static async Task AddAsync()
{
    var result = await Task.Run(() => Add(5, 6));
    Console.WriteLine("The sum is: {0}", result);
}

Upvotes: 3

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