/// <summary> /// 获取季度的第一天 /// </summary> /// <param name="month">2018Q1</param> /// <returns></returns> public static DateTime ToQuarterFirstday(string quarter) { if (quarter == "") { quarter = ConvertDateTime.ToYearQuarterString(); } int yearIndex = ConvertObject.ToInt32(quarter.Substring(0, 4)); int quarterIndex = ConvertObject.ToInt32(quarter.Substring(5, 1)); switch (quarterIndex) { case 4: return(new DateTime(yearIndex, 10, 1)); case 3: return(new DateTime(yearIndex, 7, 1)); case 2: return(new DateTime(yearIndex, 4, 1)); default: return(new DateTime(yearIndex, 1, 1)); } }