==操作员仅在某些情况下过载 [英] ==operator overload only on certain occasions

问题描述

我正在制作一个将类型作为模板的项目.如您所知，运算符==已经对char，int，string等进行了重载，但是如果用户决定传入cstring(以null终止的字符数组)，则需要为此==重载.我可以选择仅在用户使用cstring时重载operator ==，而在不使用cstring时使用默认==吗?这将如何实现?

I am making a project that takes in types as templates. The operator== is already overloaded for chars, ints, strings, etc as you know, but if the user decides to pass in a cstring (null terminated character array) I will need to overload the == for that. Can I choose to only overload the operator== when the user uses cstrings, and use the default == when they dont? How would this be accomplished?

推荐答案

对于C字符串，不能重载operator==，因为它们是指针，并且如果至少一个操作数是类或枚举，则可以重载运算符.您可以做的是创建自己的比较器函数，然后在代码中使用它，而不是使用==:

You can't overload operator== for C strings, because they are pointers and operators can be overloaded if at least one operand is a class or enum. What you can do is create your own comparator function and use it in your code instead of ==:

template<typename T>
bool my_equal(const T& a, const T& b) {
    return a == b;
}

bool my_equal(const char* a, const char* b) {
    return /* your comparison implementation */;
}

更新:正如TonyD在评论中指出的那样，您可能必须添加更多重载以支持std::string与const char*比较.

Update: you may have to add more overloads to support std::string vs const char* comparisons, as pointed out by TonyD in comments.

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