写个 LINQ的分组

// 实现多key分组的扩展函数版本

var sums = empList

         .GroupBy(x => new { x.Age, x.Sex })

         .Select(group => new {

            Peo = group.Key, Count = group.Count()

         });

foreach (var employee in sums) {

   Console.WriteLine(employee.Count + ": " + employee.Peo);

}



// 实现多key分组的lambda版本

var sums2 = from emp in empList

            group emp by new { emp.Age, emp.Sex } into g

            select new { Peo = g.Key, Count = g.Count() };

foreach (var employee in sums) {

   Console.WriteLine(employee.Count + ": " + employee.Peo);

}