C# 获取某月的第一天和最后一天

/// <summary>间隔的天数

/// 获取两个传入日期间隔的天数

/// </summary>

/// <param name="bDate">起始日期</param>

/// <param name="eDate">结束日期</param>

/// <returns></returns>

public static int getDiffDays(DateTime bDate, DateTime eDate)

{

TimeSpan ts = new TimeSpan();

ts = eDate - bDate;

return (int)ts.TotalDays + 1; //是否+1,根据需求定.

}

/// <summary>

/// 获取两个传入日期间隔的月份

/// </summary>

/// <param name="date1">起始日期</param>

/// <param name="date2">结束日期</param>

/// <returns></returns>

public int getDiffMonth(DateTime date1, DateTime date2)

{

int year1 = date1.Year;

int year2 = date2.Year;

int month1 = date1.Month;

int month2 = date2.Month;

int months = 12 * (year2 - year1) + (month2 - month1);

return months;

}

/// <summary>

/// 取得某月的第一天

/// </summary>

/// <param name="datetime">要取得月份第一天的时间</param>

/// <returns></returns>

private DateTime FirstDayOfMonth(DateTime datetime)

{

return datetime.AddDays(1 - datetime.Day);

}

//// <summary>

/// 取得某月的最后一天

/// </summary>

/// <param name="datetime">要取得月份最后一天的时间</param>

/// <returns></returns>

private DateTime LastDayOfMonth(DateTime datetime)

{

return datetime.AddDays(1 - datetime.Day).AddMonths(1).AddDays(-1);

}

//// <summary>

/// 取得上个月第一天

/// </summary>

/// <param name="datetime">要取得上个月第一天的当前时间</param>

/// <returns></returns>

private DateTime FirstDayOfPreviousMonth(DateTime datetime)

{

return datetime.AddDays(1 - datetime.Day).AddMonths(-1);

}

//// <summary>

/// 取得上个月的最后一天

/// </summary>

/// <param name="datetime">要取得上个月最后一天的当前时间</param>

/// <returns></returns>

private DateTime LastDayOfPrdviousMonth(DateTime datetime)

{

return datetime.AddDays(1 - datetime.Day).AddDays(-1);

}