Getting return value from Task.Run

Question

I have the following code:

public static async Task<string> Start(IProgress<ProcessTaskAsyncExProgress> progress)
{
    const int total = 10;
    for (var i = 0; i <= total; i++)
    {
        await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture)));
        if (progress != null)
        {
            var args = new ProcessTaskAsyncExProgress
            {
                ProgressPercentage = (int)(i / (double)total * 100.0),
                Text = "processing " + i
            };
            progress.Report(args);
        }
    }
    return "Done";
}

private static string RunLongTask(string taskName)
{
    Task.Delay(300);
    return taskName + "Completed!";
}

How do I get back the string value of RunLongTask from this line: await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture)));?

I've tried:

var val = await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture))).Result;

But I get an error saying "string is not awaitable".

Answer 1

Remove the Result from the end. When you await you will get the Result back from the await-able method.

var val = await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture)));