C ++高级拼图[关闭]

Question

我遇到了以下问题，我没有一个好主意。也许有人可以帮助我？

class Foo 
{
    // [Your code goes here] 
    // Rec1: Don’t write function call operator()
    // Rec2: Don’t use macros.
}; 
int main()
{
    Foo foo;
    foo();          // This line prints “Hello World!” 
}

Answer 1

#include <iostream>
class Foo
{
public:
    using fncPntr = void(*)(void);
    //Implicit conversion to a function pointer
    operator fncPntr()
    {
        return &Print;
    }
    void static Print()
    {
        std::cout << "Hello World!";
    }
};
int main()
{
    Foo foo;
    foo();
}

Answer 2

class Foo{
// [Your code goes here] 
};
void foo()
{
    std::cout << "hello";
}
class Bar{
// Rec1: Don’t write function call operator()
// Rec2: Don’t use macros.
};