C# 异步函数的返回值

Question

I'm trying to write a C# async function which could return a value.

Current function code:

public async void getTwitterFollowerCount()
{
    var twitterCtx = new TwitterContext(SharedState.Authorizer);

    var followers = await (from follower in twitterCtx.Friendship where follower.Type == FriendshipType.FollowerIDs && follower.UserID == "15411837" select follower).SingleOrDefaultAsync();

    if (followers != null && followers.IDInfo != null && followers.IDInfo.IDs != null)
    {
        followers.IDInfo.IDs.Count();
    }
}

I've been trying something similare to this:

public async int getTwitterFollowerCount()
{
    var twitterCtx = new TwitterContext(SharedState.Authorizer);

    var followers = await (from follower in twitterCtx.Friendship where follower.Type == FriendshipType.FollowerIDs && follower.UserID == "15411837" select follower).SingleOrDefaultAsync();

    if (followers != null && followers.IDInfo != null && followers.IDInfo.IDs != null)
    {
        return followers.IDInfo.IDs.Count();
    }
}

But never got it working. Does someone have a idea, how I could be able to return a value from this async function?

Would appreciate any kind of help.

Answer 1

Change return type of getTwitterFollowerCount to Task<int> . Read more at MSDN https://msdn.microsoft.com/en-us/library/mt674882.aspx .

Answer 2

As others have indicated,

Task<int>

is the correct return type.

Also, never have an 'async void' method if you can avoid it since it's impossible to await a method that returns void. The only case where you should do this is with event handlers. Otherwise, always return 'Task'.