Pointers and Structures

This post discusses the basics of pointers and Structures.

POINTERS:

A pointer stores the address of a variable. It can also be used to store the address of an array, structure(which is a user defined variable), function and even a pointer.
Declaration:
A pointer for custom type variables is defined as:
int * p(where p is the pointer we are using)
float *p
char *p
A pointer for a structure:
Lets say the structure is named struct student {
int m_iinfo;
char m_pname;}
the pointer will be defined as struct student *p;

A pointer to a function:
A pointer to a function is defined and can be used only for the same TYPE of functions.
Same type functions are those who have the same return types and have same arguements.
Example:
int func(int x, int y) be the function.
pointer to the function will be : int (*p)(int x, int y);
Always remember the braces for the pointer p. If there are no braces, it will be treated as a function p whose return type is an integer pointer and arguements are integers. This type of notation is extensively used for interface with OS and registers to point to a particular function.

Pointers to pointers:
int *p is a pointer to an integer. We can also create q which is a pointer to an integer pointer.
int ** q defines a pointer q to an integer pointer.
it is equivalent to a two dimensional array. This type of declaration is called COMPLEX DECLARATION.