相同的GetHashCode()用于不同的对象 [英] Same GetHashCode() for different objects

问题描述

执行这段代码后:

int a = 50;
float b = 50.0f;
Console.WriteLine(a.GetHashCode() == b.GetHashCode());

我们得到False，这是预期的，因为我们正在处理不同的对象，因此我们应该获得不同的哈希值.

We get False, which is expected, since we are dealing with different objects, hence we should get different hashes.

但是，如果我们执行此操作:

However, if we execute this:

int a = 0;
float b = 0.0f;
Console.WriteLine(a.GetHashCode() == b.GetHashCode());

我们得到True.两个对象都返回相同的哈希码:0.

We get True. Both obejcts return the same hash code: 0.

为什么会这样?他们不应该返回不同的哈希值吗?

Why does this happen? Aren't they supposed to return different hashes?

推荐答案

System.Int32的GetHashCode类似于:

public override int GetHashCode()
{
    return this;
}

当然是0，它将返回0.

System.Single的(float是别名)GetHashCode是:

public unsafe override int GetHashCode()
{
    float num = this;
    if (num == 0f)
    {
        return 0;
    }
    return *(int*)(&num);
}

就像您看到的那样，在0f它将返回0.

Like you see, at 0f it will return 0.

使用的程序是ILSpy.

Program used is ILSpy.

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