C# 如何在 Linq 中获得 SUM？
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时间：2020-08-10 00:33:01 来源:igfitidea点击:
how to get a SUM in Linq?
提问by gurehbgui
I need to do the following, I have a Listwith a class which contains 2 integer id and count
我需要执行以下操作，我有一个List包含 2 个整数 id 和计数的类
Now I want to do the following linq query:
现在我想做以下 linq 查询：
get the sum of the count for each id
but there can be items with the same id, so it should be summerized e.g.:
但是可以有具有相同 id 的项目，因此应该对其进行汇总，例如：
id=1, count=12
id=2, count=1
id=1, count=2
sould be:
应该是：
id=1 -> sum 14
id=2 -> sum 1
how to do this?
这该怎么做？
采纳答案by dtb
回答by zey
Try it ,
尝试一下 ，
.GroupBy(x => x.id)
.Select(n => n.Sum(m => m.count));
回答by Branko Dimitrijevic
The following program...
下面的程序...
struct Item {
public int Id;
public int Count;
}
class Program {
static void Main(string[] args) {
var items = new [] {
new Item { Id = 1, Count = 12 },
new Item { Id = 2, Count = 1 },
new Item { Id = 1, Count = 2 }
};
var results =
from item in items
group item by item.Id
into g
select new { Id = g.Key, Count = g.Sum(item => item.Count) };
foreach (var result in results) {
Console.Write(result.Id);
Console.Write("\t");
Console.WriteLine(result.Count);
}
}
}
...prints:
...印刷：
1 14
2 1
