如何獲得每個月的總和？

Question

A有一個包含9月，10月，11月的集合列表但是我想特別添加每個月

Start Time                    EndTime
September 11,2016 5:00PM   September 11,2016 8:00PM  
September 12,2016 10:00AM  September 12,2016 8:00PM 
October 1,2016 5:00PM      September 11,2016 8:00PM  
October 2,2016 10:00AM     September 12,2016 8:00PM 
November 1,2016 5:00PM     November 11,2016 8:00PM  
November 2,2016 10:00AM    November 12,2016 8:00PM 

我的代碼

List<MonthHours> oList=new List<MonthHours>();
Int total=0;
TimeSpan span=new TimeSpan();
foreach(var data in oList)
{
Span=data.EndTime-data.StartTime;
Total+=span.hours;
}

我得到了所有的金額從9月到11月，我真正想要的是得到月份的總和例子在9月我得到3個小時，10月5日，11月5個小時。

對不起新手TIA

Answer 1

var result = oList
    .GroupBy(data => data.StartTime.ToString("MMMM"))
    .Select(g => new MonthHours {
        Month = g.Key,
        Total_Hours = g.Sum(d => (d.EndTime - d.StartTime).TotalHours)
    });

foreach (var month in result) {
    var str = string.Format("Month : {0}, Total Hours : {1}", month.Month, month.Total_Hours);
}

Answer 2

按日期列出按日期分組然后選擇所有差異的每個摘要

var grouped = oList.GroupBy(d=>StartTime.Month).Select(c=>c.Sum(d=>(d.EndTime-d.StartTime)).ToArray();