pointers

/*
 ============================================================================
 Name        : pointers.c
 Author      : 
 Version     :
 Copyright   : Your copyright notice
 Description : Hello World in C, Ansi-style
 ============================================================================
 */

//Pointers -- point to ADDRESS of RAM. Can be data or function
//2 operations
//You may wish to change what you are pointing to
//You may wish to read/write/execute the data/function you are pointing to
//this is done by dereferencing aka go to address you are pointing to

//When declaring a pointer size allocated is always 4 bytes as we hold an address in memory
#include <stdio.h>

int main () {

   int  var = 20;
   int x = 10;
   int  *ip;        /* pointer variable declaration */

   ip = NULL; // Point to address 0 for safety
   ip = &var;  /* Change where you point to. Now pointing to address of var */

   x = x + *ip; // x = 10 + 20. grabbing data where pointer is pointing is called dereferencing the pointer

   ip = &x; //CHANGE WHERE ip points --> point to address of x

   //showing pointer calculation
   ip = ip + 3;  // address of ip + (3 * sizeof(int)) = address of ip + 12

   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;
}