What is a Pointer in C++ || C plus plus || PART-I (Stack Pointers)

Memory of a program :
                               The memory of a program in C++ is composed of 2 units :
1. Stack : A static memory and we kinda define its size before the program executes.
2. Heap : A dynamic memory. It is most beneficial when you have various inputs and you can't define their size before execution.

What is a pointer?
                            A pointer stores the address of a variable. For example,

int a = 5;    // variable
int* a_pointer = &a;  //* differentiates it as a pointer. & is used to get the address.

Now we have stored the address of 'a' variable in 'a_pointer'. Moreover, if you cout 'a_pointer' then you'll have the same output as in case of cout << &a that is the address of 'a' variable.
int* serves as the data type for a pointer of type int.
If you want to print the data stored in 'a' using 'a_pointer', you can do it by using * while printing i.e.

cout << *a_pointer; 

Similarly, if you are upto storing the address of a char data type then :

char b = 'X';
char* b_pointer = &b;

cout << b_pointer;  //address of b is displayed

Remember that pointer of any data type is of 4 bytes despite the fact that it is char, int or float. Address are displayed as 8 characters hexadecimal number. 

Note : & and * are opposites of each other. This means :

        int a = 5;
        cout << *(&a);   //Displays the data in 'a' since & and * have cancelled out with each other.

Similarly, you can store the address of a pointer into another pointer as :

int A = 5;
int* A_ptr = &A;
int** A_ptr2 = &A_ptr;

Now in this case, As we moved onto a pointer who was pointing a another pointer, we got int**. Likewise, a third-stage pointer would be int*** and goes on!


In the next part, we'll discuss arrays as pointers.

Comment below if you have any confusions. Thanks! :)