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<student> studentlist1 = newlist<student>() {
        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<student> studentlist2 = newlist<student>() {
        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<student>
  {
    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