c# - 如何从 List 中获取重复次数

Question

List<int> ListIdProducts = new List<int>();
var IdProductKey = from a in me.ProductKeywords where a.Keyword == item.Id select a;
 foreach (var item2 in IdProductKey)
 {
   ListIdProducts.Add(item2.Product.Value);
 }

结果是:5个6个75个2个5

我需要得到以下 5=3, 6=1, 7=1, 2=1

Answer 1

使用GroupBy LINQ 方法:

ListIdProducts
    .GroupBy(i => i)
    .Select(g => new { Value = g.Key, Count = g.Count() });