[转][C#] async 使用方法

private async void button1_Click(object sender, EventArgs e)
{
    var maxValue = 200;
    var result = await SumAsync(maxValue);
    MessageBox.Show(this, result.ToString(), "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
} 

private async Task<string> SumAsync(int maxValue)
{
    string result = string.Empty;
    await Task.Run(() =>
    {
        for (int i = 0; i<maxValue; i++)
        {
            result += i.ToString() + ",";
            Thread.Sleep(100);
        }
    });
    return result;
}