c++ - 为指针/共享指针和其他类型重载流 << 运算符

Question

是否可以重载自定义类的 << 运算符，使其能够满足以下所有条件:

CustomClass customClass;
std::shared_ptr<CustomClass> sharedPointer(customClass);

os << customClass;
os << sharedPointer;

或者至少以下工作:

os << sharedPointer.get();

默认情况下，使用通用技术重载 operator , 只有以下 2 个选项有效:

os << customClass;
os << *sharedPointer.get();

编辑

这里的“工作”意味着，在所有情况下，自定义类 <<运算符重载被执行，我得到了 os << customClass 的结果在所有情况下代替指针类的指针地址

示例

代码:

os << customClass;
os << sharedPointer;
os << sharedPointer.get();
os << *sharedPointer.get();

输出:

Custom class text
00000244125655C0
00000244125655C0
Custom class text

期望:

第二个或第三个输出也应该是“自定义类文本”

Answer 1

that in all cases the custom classes << operator overload is executed and that I get the result of os << customClass in all cases instead of pointer addresses in the case of the pointer classes

这是我的做法:

#include <iostream>
#include <string>
#include <memory>

class MyClass {
    std::string s;

    friend std::ostream& operator<<(std::ostream& os, const MyClass& c) {
        os << c.s;
        return os;
    }

public:
    MyClass(const std::string& s_) : s(s_) {}
};

template<typename T>
std::ostream& operator<<(std::ostream& os, const std::shared_ptr<T>& pc) {
    os << pc.get() << " " << *pc;
    return os;
}    


int main() {
    std::shared_ptr<MyClass> pc = std::make_shared<MyClass>("Hello");
    std::cout << pc << std::endl;
}

输出

0x20f5c30 Hello

查看 live example .