CP : Pointer explanation

What are the Pointers?

A pointer is a variable whose value is the address of another variable, i.e., direct address of the memory location.

The general form of a pointer variable declaration is −

type *var-name;

type is the pointer's base type

var-name is the name of the pointer variable

asterisk * used to declare a pointer is the same asterisk used for multiplication.

Take a look at some of the valid pointer declarations −

int    *ip;    /* pointer to an integer */
double *dp;    /* pointer to a double */
float  *fp;    /* pointer to a float */
char   *ch     /* pointer to a character */

How to Use Pointers?

There are a few important operations, which we will do with the help of pointers very frequently. 

(a) We define a pointer variable, 

(b) assign the address of a variable to a pointer and 

(c) finally access the value at the address available in the pointer variable. 

This is done by using unary operator * that returns the value of the variable located at the address specified by its operand. The following example makes use of these operations −

EXAMPLE: 

#include <stdio.h>

int main () 

{

   int  var = 20;   /* actual variable declaration */

   int  *ip;        /* pointer variable declaration */

   ip = &var;  /* store address of var in pointer variable*/

   

  printf("Address of var variable: %x\n", &var  );

  /* address stored in pointer variable */

  printf("Address stored in ip variable: %x\n", ip );

   /* access the value using the pointer */

   printf("Value of *ip variable: %d\n", *ip );

   return 0;

}

Reference operator (&) and Dereference operator (*)

" & "is calledthe reference operator. It gives you the address of a variable.

Likewise, there is another operator that gets you the value from the address, it is called a dereference operator " *."

Explanation