C#中的異步調用

這個示例是在Winform裏做的，大家可以參考：

//定義聲明委託
private delegate string returnresult(int i, long b);
/// <summary>
/// 同步執行事件
/// </summary>
private void button3_Click(object sender, EventArgs e)
{
    returnresult sl = sss;
    string ssa = sl.Invoke(0, 1000000101);//只有等待
    MessageBox.Show(ssa);
}
private string sss(int a, long b)
{
    long s = 0;
    for (long o = a; o < b; o++)
    {
        s += o;
    }
    return s.ToString().Trim();
}
/// <summary>
/// 異步執行時間
/// </summary>
private void button5_Click(object sender, EventArgs e)
{
    returnresult dd = sss;
    AsyncCallback sas = new AsyncCallback(asiresult);
    dd.BeginInvoke(0, 1000000101, sas, dd);//照樣運行
    MessageBox.Show("照樣運行！！！");
}
/// <summary>
/// 回調函數
/// </summary>
/// <param name="asa"></param>
private void asiresult(IAsyncResult asa)
{
    returnresult aass = asa.AsyncState as returnresult;
    MessageBox.Show(aass.EndInvoke(asa));
}