通过循环列表中的列表获得总和c#

使用LINQ

var totalQty = 0;
foreach (var item in ItemIDList)
{
    var sumOfCurrentItem = GrnList.SelectMany(s => s.GRNDetails
                           .Where(f => f.ItemID == item)).Select(f => f.RecevedQty).Sum();

    totalQty += sumOfCurrentItem ;
}

或者甚至是一个衬里更换 foreach循环(Credit转到ReSharper :))

int totalQty = ItemIDList.Sum(item => GrnList
                  .SelectMany(s => s.GRNDetails.Where(f => f.ItemID == item))
                  .Select(f => f.RecevedQty).Sum());