C#中的Linq Intersect与Except方法使用实例

实例描述

现有某班学生的两份成绩，两份成绩中存在一些不一致的记录。需借助于编程方法找出这些不一致的记录。

实例代码

using System;
using System.Collections.Generic;
using System.Linq;
namespace IntersectAndExceptExp
{
  class Program
  {
    static void Main(string[] args)
    {
      List studentList1 = newList() {
 new Student(){StudentId=1,Score=64},
 new Student(){StudentId=2,Score=85},
 new Student(){StudentId=3,Score=78},
 new Student(){StudentId=4,Score=94},
 new Student(){StudentId=5,Score=90}
      };
      List studentList2 = newList() {
 new Student(){StudentId=1,Score=64},
 new Student(){StudentId=2,Score=80},
 new Student(){StudentId=3,Score=78},
 new Student(){StudentId=4,Score=94},
 new Student(){StudentId=5,Score=95}
      };
      var both = studentList1.Intersect(studentList2,new StudentComparer());
      var diff1 =studentList1.Except(both, new StudentComparer());
      var diff2 =studentList2.Except(both, new StudentComparer());
      Console.WriteLine("-------------下面是两份成绩中不同的记录--------------");
      Console.WriteLine("-------------第一份学生成绩--------------");
      foreach (var s in diff1)
      {
 Console.WriteLine("StudentId:"+s.StudentId+";Score:"+s.Score);
      }
      Console.WriteLine("-------------第一份学生成绩--------------");
      foreach (var s in diff2)
      {
 Console.WriteLine("StudentId:"+ s.StudentId + ";Score:" + s.Score);
      }
    }
  }
  public class Student
  {
    public int StudentId { get; set; }
    public int Score { get; set; }
  }
  public class StudentComparer : IEqualityComparer
  {
    public bool Equals(Student x, Studenty)
    {
      if (Object.ReferenceEquals(x, y)) returntrue;
      return x != null && y != null&& x.StudentId == y.StudentId && x.Score == y.Score;
    }
    public int GetHashCode(Student obj)
    {
      int hashStudentId =obj.StudentId.GetHashCode();
      int hashScore =obj.Score.GetHashCode();
      return hashStudentId ^ hashScore;
    }
  }
}

代码说明

先使用Intersect方法生成两份记录的交集，该方法会使用传入的比较器对值进行比较决定记录是否相同。基于前步生成的交集，再使用Except方法找出两份记录中不一致的记录，该方法同样使用传入的比较器对值进行比较决定记录是否相同。

执行结果