Cannot implicitly convert type 'int' to '... Tasks <int>'

Question

if it is asynchronous, it will return without errors, why it throws an error without async, async is useless in this operation.

public Task<int> countUp() { string compare = txtTag.Text; int count = 0; for (int i = 0; i < dataGridView1.Rows.Count; i++) { if (compare == dataGridView1[0, i].Value.ToString()) { BeginInvoke(new Action(() => { count++; txtCount.Text = count.ToString(); })); } } return count; } 

Answer 1

Well, you can return the completed task:

 return Task.FromResult(count); 

http://msdn.microsoft.com/en-us/library/hh194922.aspx

Why you want to return the task is a bit of a mystery. Conceptually, a task is a promise that something will happen in the future. In your case, this has already happened, so using the task is completely pointless.

Answer 2

As the error clearly states, you cannot return int as Task<int> . (unless you make an async method that does compile-time magic to create a Task<T> .

If your method is not asynchronous, you should not return Task<T> in the first place.
Instead, just return int directly.

If for some reason you need to return Task<T> , you can call Task.FromResult() to create a finished task with a given value.

Answer 3

There is nothing in this method indicating that it is an asynchronous method, except that you have told it that it returns a Task<int> .

However, you do not return Task<int> , you return count , int .

Since you are not waiting for the action to complete, I would remove the type of the returned Task<int> and replace it with just int , since this method is completely synchronous (except for the part that you do not expect anyway).

Answer 4

The code here is clearly incorrect. Try looking at the return type in your code. You are returned and int that do not match the return type expecting a Task<int> . If you are not going to use async in this method, you can simply change your return type to int .

However, if you insist on returning the Task<int> instead of int , you can use the following for the return statement

 return Task.FromResult(count) 

This will translate the int to Task<int> . For more information on Task.FromResult you can visit: https://msdn.microsoft.com/en-us/library/hh194922(v=vs.110).aspx What is used for Task.FromResult <TResult> in C #