为什么不只在平等中使用GetHashCode?

问题描述

鉴于人员类别:

class person
{
    public string name;
    public int age;
}

说，我重写了类人的GetHashCode方法:

say, i override the class person`s GetHashCode method:

 public override int GetHashCode()
 {
     unchecked
     {
          hashCode = 17;
          // ...some code here...
     }
     return hashCode;
 }

并且基于msdn的指令，我还需要重写Equality，所以我这样做了:

and based on msdn`s instruction, i also need to override the Equality, so i did this:

public override bool Equals(object obj)
{
    // ...something like: 
    return this.name == (person)obj.name && this.age ==(person)obj.age;
}

嘿，等等，我可以得到人实例的哈希码，为什么不仅仅在Equals中使用哈希码呢?像:

hey, wait, sine i can get the hashcode of the person instance, why not just using hashcode in Equals? like:

public override bool Equals(object obj)
{
    return this.GetHashCode() == (person)obj.GetHashCode();
}

我在Google上搜索后发现，大多数Equals()示例都与我以前的Equals()版本相似，所以我误会了吗?

i googled and found that most Equals() examples are similar with my previous edition of Equals(), so, am i misunderstood something?

任何帮助，谢谢.

推荐答案

不能保证两个不相等的对象具有不相等的哈希码(称为冲突).这就是 MSDN 说:

Two unequal objects are not guaranteed to have unequal hashcodes (that's called a collision).This is what MSDN says:

如果两个对象比较相等，则每个对象的GetHashCode方法必须返回相同的值.但是，如果两个对象的比较不相等，则两个对象的GetHashCode方法不必返回不同的值.

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