C ++对象等同 [英] C++ object equality

问题描述

我有一个类 MyCloth 和该类的一个对象实例，像我这样实例化：

I have a class MyCloth and one one object instance of that class that I instantiated like this:

MyCloth** cloth1;

在程序中的某一点，我会做这样的事情：

And at one point in the program, I will do something like this:

MyCloth** cloth2 = cloth1;

然后在某个时候，我想检查 cloth1 和 cloth2 是相同的。 （类似Java中的对象平等，只有在这里， MyCloth 是一个非常复杂的类，我不能构建 isEqual function。）

And then at some point later, I want to check to see if cloth1 and cloth2 are the same. (Something like object equality in Java, only here, MyCloth is a very complex class and I can''t build an isEqual function.)

我如何做这个相等检查？我想可能检查他们是否指向相同的地址。这是个好主意吗？

How can I do this equality check? I was thinking maybe checking if they point to the same addresses. Is that a good idea? If so, how do I do that?

推荐答案

您可以通过比较地址由两个指针保持。你提到Java;这与类似于两个引用相等的测试。

You can test for object identity by comparing the addresses held by two pointers. You mention Java; this is similar to testing that two references are equal.

MyCloth* pcloth1 = ...
MyCloth* pcloth2 = ...
if ( pcloth1 == pcloth2 ) {
    // Then both point at the same object.
}   

您可以通过比较对象两个对象的内容。在C ++中，这通常通过定义 operator == 来完成。

You can test for object equality by comparing the contents of two objects. In C++, this is usually done by defining operator==.

class MyCloth {
   friend bool operator== (MyCloth & lhs, MyCloth & rhs );
   ...
};

bool operator== ( MyCloth & lhs, MyCloth & rhs )
{
   return ...
}

使用operator ==定义，可以比较等式：

With operator== defined, you can compare equality:

MyCloth cloth1 = ...
MyCloth cloth2 = ...
if ( cloth1 == cloth2 ) {
    // Then the two objects are considered to have equal values.
}   

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