C Pointers

A pointer is an integer which designates the location in memory.

int* pA ; // declares a pointer to an integer in a pointer variable. 

The position "*" is flexible.  You can declare a pointer as such too:

int * pA or int *pA

The form int* is more natural as it is easy to call out the type of pA is int*

To initialize a pointer to NULL,

int *pA = 0 or int *pA = NULL

Note that *pA when used outside of declaration means the thing pointer pA points to.  This allows you to access the item at the far end of the pointer and "*" is called dereferencing the pointer.

An object is implemented using pointer.  However, you never dereferencing an object when used.  You just use the name of the object.

Pointer of type void* is a generic pointer.  It can point to anything.  Effectively, pointer to void bypass type checking.  Both array and string in C are pointers.

To obtain a pointer from a variable, use the address (&) operator.  For example

int result = 0;
pA = &result;

int** ptr; // declare a pointer to a pointer

To create a pointer to a function, just use the function name without the parameters.  For example

int square(int a, int b);
&square is the pointer to the function square