Pointers 101

#include <stdio.h>

/***************************************************************
*                Voodoo 'Doll' Petskull                        *
*               petskull@twistedport.com                       *
*              http://www.twistedport.com                      *
*--------------------------------------------------------------*
*--pointers101.c--                                             *
*-----------------                                             *
*     Shooting for my 'Expert Pointers Merit Badge'            *
*     Things to remember:                                      *
*     '*' means 'Dereference' (Given a pointer, get the        *
*                              thing referenced)               *
*     '&' means 'Address of'  (Given a thing, point to it)     *
*     ----------------------------------------------------     *
*     thing       | Simple thing (variable)                    *
*     &thing      | Pointer to variable 'thing'                *
*     thing_ptr   | Pointer to an integer (may or may not be   *
*                 |                        specific integer    *
*                 |                       'thing')             *
*     *thing_ptr  | Integer at the address that 'thing_ptr'    *
*                 | points to                                  *
*                                                              *
***************************************************************/

int thing;        /* define a thing */
int *thing_ptr;    /* define a pointer to a thing */

int main(){

 thing = 14;       /* the box 'thing' now contains the value '14' */
 printf("The value of 'thing' is: %d\n", thing);

 thing_ptr = &thing;     /* Assigns the address(&) of 'thing' to the pointer 'thing_ptr' */
 *thing_ptr = 8;        /* thing_ptr points to the memory allocated to the variable 'thing',*/
                 /* so- by changing the value in that memory to '8'- 'thing' now equals '8' */
 printf("The value of 'thing' is now: %d\n", thing);

 return(0);
}

#include "myheader.h"
int main(void) {
  int param = 5;
  func_by_pointer(& param);
  func_by_reference(param);
  return 0;
}