如何重载operator ==（）为类的指针？ [英] How to overload operator==() for a pointer to the class?

问题描述

我有一个类 AString 。这是很基本的：

I have a class called AString. It is pretty basic:

class AString
{
public:
    AString(const char *pSetString = NULL);
    ~AString();
    bool operator==(const AString &pSetString);
    ...

protected:
    char *pData;
    int   iDataSize;
}

现在我要写如下代码：

Now I want to write code like this:

AString *myString = new AString("foo");
if (myString == "bar") {
    /* and so on... */
}

但是，现有的比较运算符只支持

However, the existing comparison operator only supports

if (*myString == "bar")

如果我省略了星号，编译器不开心。

If I omit that asterisk, the compiler is unhappy.

有一种方法允许比较运算符比较 * AString 与 const char *

Is there a way to allow the comparison operator to compare *AString with const char*?

推荐答案

不，没有。

重载 operator == ，您必须提供一个用户定义的类型作为操作数和指针之一（ AString * 或 const char * ）不符合条件。

当比较两个指针时，编译器有足够的内置 operator == ，因此不会考虑将其中一个参数转换为类类型。

To overload operator==, you must provide a user-defined type as one of the operands and a pointer (either AString* or const char*) does not qualify.
And when comparing two pointers, the compiler has a very adequate built-in operator==, so it will not consider converting one of the arguments to a class type.

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