array of pointer and nested class

[AoZplusplus]

Hi, what is the difference when I call the first element (ptr[0]) of the two arrays, respectively:
someclass *ptr = arr[3]

someclass *ptr[3] (Then initialize each ptr with "new")

Another question is for nested class, can the outer class call the private data member or function of the inner class?


Thanks!

[Mathhead200]

This sounds like a homework question, but...

someclass *ptr = arr[3]; //this is the same as

someclass *ptr; //creates a pointer (to a someclass object)
ptr = arr[3]; //takes the pointer in arr[3] and stores it in ptr
              //(this means the 4th element of the array "arr" is a pointer) 

someclass *ptr[3]; //creates an array of someclass pointers (length 3)

//i.e.
ptr[0]; //refers to a someclass pointer
*ptr[0]; //refers to a someclass object
ptr; //is a pointer to a someclass pointer (the first in the array of someclass pointers) 

[AoZplusplus]

Yeah, thank you Mathhead! I feel stupid. Then what about the second question?

[Mathhead200]

I've never tried that in C++ without declaring the classes as friends, by in java the answer would be yes. Just whip up some test code like:

class Outer {
    class Inner {
     private:
        int field;
        void method();
    } inner;
} outer;

int main() {
    outer.inner.field;
    outer.inner.method();
}

[AoZplusplus]

The outcome turned out to be negative, thanks!