计算本周周一周日

/// <summary>   
/// 计算本周周一
/// </summary>   
/// <param name="date">该周中任意一天</param>   
/// <returns></returns>   
public static DateTime GetMondayDate(DateTime date)
{
    int i = DayOfWeek.Monday - date.DayOfWeek;
    if (i == -1) i = 6;
    return date.AddDays(i);
}
/// <summary>   
/// 计算本周周日
/// </summary>   
/// <param name="date">该周中任意一天</param>   
/// <returns></returns>   
public static DateTime GetSundayDate(DateTime date)
{
    int i = date.DayOfWeek - DayOfWeek.Sunday;
    if (i != 0) i = 7 - i;
    return date.AddDays(i);
}