Pointers

[MAhmed]

trying to make a pointer which call function from human class but having difficulties please check below on line number 28-29

  #include<iostream>
using namespace std;

class human
{
public:
	void fun()
	{
		cout << "Human\n";
	}
};
class man : public human
{
public:
	void fun()
	{
		cout << "Man\n";
	}
};

void main()
{
	human h1;
	man m1;
	h1.fun();
	m1.fun();

	human* ptr;
	ptr->&fun();
}

[JayhawkZombie]

ptr->&fun(); should be ptr->fun();

But you didn't make that pointer point to anything.
You need to make that pointer point to something.

human *ptr = &h1;
or
human *ptr = &m1;
will both work, but what do you think will happen if you do

human *ptr = &m1;
ptr->fun();

Which "fun" will be called?

[edge6768]

human* ptr creates a pointer to a human (or derived type), but does not create an instance of a human (or derived type). You will need to can call the objects constructor like so:

human* ptr = new human();
// OR
human* ptr = new man();

Additionally, you will need to make the fun() method virtual so that the derived class can override it.

To call the function you should just use ptr->fun();

[JayhawkZombie]

No, you don't need to create a new one. You can have the pointer point to an instance that already exists, like in the code I showed above.

You CAN (and then of course make you to delete it), but to use a pointer you can make a new one or make it point to an instance of that class you created earlier (which then of course you don't call delete on).