Go4Expert - how can i access i private data member in main

Three ways, two legal one not. 1. Call the accessor function; 2. Make main a friend of the class and access the member directly. 3. Work out the address of the member and access its memory directly.

Code:

class PrivTestCls

{

private:

        int a;

        int b;

        int c;



public:

        PrivTestCls(int _a,int _b,int _c) { a=_a; b=_b; c=_c; }

        int get_a() { return a; }

        friend void privtest();

};



void privtest()

{

        PrivTestCls x(1,2,3);

        printf("a=%d\n",x.get_a()); // we can do this without being a friend

        printf("b=%d\n",x.b); // we can do this because we're a friend



        // this defeats private but the syntax makes it pretty obvious that's what's happening

        int *ptr2=(int*)&x;

        printf("c=%d\n",ptr2[2]);

}

In reality if your application design requires you to access c then you must create an accessor function or make the accessing function a friend. But if the class design prevents it then you will have to negotiate with the class designer; perhaps he can suggest an alternative design that doesn't require you to access the private data.