GroupBy分组后，如何获取值？

[se344]

class Program
{       
    static void Main(string[] args)
    {
        List<Person> ListP = new List<Person>() 
        {
            new Person(){Age = 10,Name = "张三"},
            new Person(){Age = 10,Name = "李四"},
            new Person(){Age = 20,Name = "王二"},
            new Person(){Age = 20,Name = "麻子"},
        };
        var ccc = ListP.GroupBy(x => x.Age);
    }
}
public class Person
{
    public int Age;
    public string Name;
}

上面的代码，按照Age，对ListP进行分组，我想问的是：
通过ccc，如果获取到年龄是10的那个分组的两个Person对象，就是"张三"和"李四"那两个..............

[全栈极简]

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Person> ListP = new List<Person>() 
            {
                new Person(){Age = 10,Name = "张三"},
                new Person(){Age = 10,Name = "李四"},
                new Person(){Age = 20,Name = "王二"},
                new Person(){Age = 20,Name = "麻子"},
            };
            var ccc = ListP.GroupBy(x => x.Age).ToArray();
            var persons = ccc.FirstOrDefault(x => x.Key == 10).ToArray();
            foreach (var item in persons)
            {
                Console.WriteLine("{0},{1}", item.Age, item.Name);
            }
        }
    }

    public class Person
    {
        public int Age;
        public string Name;
    }
}

[以专业开发人员为伍]

借用楼上的代码，可以写为

static void Main(string[] args)
{
    List<Person> ListP = new List<Person>()
    {
        new Person(){Age = 10,Name = "张三"},
        new Person(){Age = 10,Name = "李四"},
        new Person(){Age = 20,Name = "王二"},
        new Person(){Age = 20,Name = "麻子"},
    };
    var ccc = ListP.GroupBy(x => x.Age).Where(x => x.Key == 10).SelectMany(x => x);
    foreach (var item in ccc)
    {
        Console.WriteLine("{0},{1}", item.Age, item.Name);
    }
}
}

public class Person
{
public int Age;
public string Name;
}

你可以调试一下 ccc 变量的类型，它就是 Person 的列表。

[以专业开发人员为伍]

其实，我更喜欢“傻瓜化的” 类sql的写法。我觉得许多时候能把代码写得傻瓜都懂，这才是真正的聪明。 这个查询可以写成类似 sql 的写法

static void Main(string[] args)
{
    List<Person> ListP = new List<Person>()
    {
        new Person(){Age = 10,Name = "张三"},
        new Person(){Age = 10,Name = "李四"},
        new Person(){Age = 20,Name = "王二"},
        new Person(){Age = 20,Name = "麻子"},
    };
    var ccc = from x in ListP
                group x by x.Age into g
                where g.Key == 10
                from p in g
                select p;
    foreach (var item in ccc)
    {
        Console.WriteLine("{0},{1}", item.Age, item.Name);
    }
}
}

public class Person
{
public int Age;
public string Name;
}

这就是聪明的 Linq。而函数式的 Linq 写法只在必要时、可以少用为妙。

[ajianchina]

引用 7 楼 以专业开发人员为伍的回复:

其实，我更喜欢“傻瓜化的” 类sql的写法。我觉得许多时候能把代码写得傻瓜都懂，这才是真正的聪明。 这个查询可以写成类似 sql 的写法

static void Main(string[] args)
{
    List<Person> ListP = new List<Person>()
    {
        new Person(){Age = 10,Name = "张三"},
        new Person(){Age = 10,Name = "李四"},
        new Person(){Age = 20,Name = "王二"},
        new Person(){Age = 20,Name = "麻子"},
    };
    var ccc = from x in ListP
                group x by x.Age into g
                where g.Key == 10
                from p in g
                select p;
    foreach (var item in ccc)
    {
        Console.WriteLine("{0},{1}", item.Age, item.Name);
    }
}
}

public class Person
{
public int Age;
public string Name;
}

这就是聪明的 Linq。而函数式的 Linq 写法只在必要时、可以少用为妙。

记得你上次在关于语法糖的帖子里还对语法糖加以推崇，那么这里前面用lambda表达式了，你咋又不推荐语法糖了呢？

[Forty2]

foreach(var group in ccc) { foreach(var person in group) { } }

[娃都会打酱油了]

var ccc = ListP.GroupBy(x => x.Age);
foreach(var g in ccc)
{
  var key = g.Key,
  var arr = g.ToArray();
}

[bdmh]

            foreach (var v in ccc)
            {
                if (v.Key == 10)
                {
                    MessageBox.Show("ok");
                }
            }

[bdmh]

或者

ccc.Where(v => v.Key == 10);