#region 得到一个月的第一天和最后一天的日期

/// <summary>

/// 得到本月的第一天日期

/// </summary>

/// <returns>DateTime</returns>

public static DateTime GetFirstDayOfMonth()

{

return GetFirstDayOfMonth(DateTime.Now);

}

/// <summary>

/// 得到本月的最有一天的日期

/// </summary>

/// <returns>DateTime</returns>

public static DateTime GetLastDayOfMonth()

{

return GetLastDayOfMonth(DateTime.Now);

}

/// <summary>

/// 得到一个月的第一天

/// </summary>

/// <param name="someday">这个月的随便一天</param>

/// <returns>DateTime</returns>

public static DateTime GetFirstDayOfMonth(DateTime someday)

{

int totalDays = DateTime.DaysInMonth(someday.Year, someday.Month);

DateTime result;

int ts = 1 - someday.Day;

result = someday.AddDays(ts);

return result;

}

/// <summary>

/// 得到一个月的最后一天

/// </summary>

/// <param name="someday">这个月的随便一天</param>

/// <returns>DateTime</returns>

public static DateTime GetLastDayOfMonth(DateTime someday)

{

int totalDays = DateTime.DaysInMonth(someday.Year, someday.Month);

DateTime result;

int ts = totalDays - someday.Day;

result = someday.AddDays(ts);

return result;

}

#endregion