c＃交叉连接两个相同类型的列表

Question

所以这里有一些代码，可以正常工作。但是我想将select部分更改为其他内容，我不确定可以使用任何其他方法的任何帮助。

using System;
using System.Linq;
using System.Collections.Generic;

public class Program
{
    public static void Main()
    {
        var all = new List<People>{new People{Id = 1, Name = "andy1", }, new People{Id = 2, Name = "andy2", }, new People{Id = 3, Name = "andy3", }, new People{Id = 4, Name = "andy4", }, };
        var someOfThem = new List<People>{new People{Id = 1, Name = null, }, new People{Id = 2, Name = null, }};
        var test = someOfThem.Select(c =>
        {
            c.Name = all.Find(a => a.Id == c.Id).Name;
            return c;
        });
        foreach (var item in test)
            Console.WriteLine("{0}={1}", item.Id, item.Name);
    }
}

public class People
{
    public int Id
    {
        get;
        set;
    }

    public string Name
    {
        get;
        set;
    }
}

这是结果。

1=andy1
2=andy2

我只是想知道还有另一种方法可以达到相同的结果，但是更优雅？还是更简单的方法？

        var test = someOfThem.Select(c =>
        {
            c.Name = all.Find(a => a.Id == c.Id).Name;
            return c;
        });

Answer 1

您可以使用C＃的LINQ和与其关联的join关键字：

using System;
using System.Linq;
using System.Collections.Generic;

public class Program
{
    public static void Main()
    {
        var all = new List<People> { new People { Id = 1, Name = "andy1", }, new People { Id = 2, Name = "andy2", }, new People { Id = 3, Name = "andy3", }, new People { Id = 4, Name = "andy4", }, };
        var someOfThem = new List<People> { new People { Id = 1, Name = null, }, new People { Id = 2, Name = null, } };
        var test = from item in someOfThem
                   join element in all on item.Id equals element.Id
                   select element;

        foreach (var item in test)
            Console.WriteLine("{0}={1}", item.Id, item.Name);
    }
}

public class People
{
    public int Id
    {
        get;
        set;
    }

    public string Name
    {
        get;
        set;
    }
}