/*
**   Program name: pointers.c
**   Purpose: to make pointers in C easy to understand. 
**
**   This program was created by
**           Scott Wenger
**           Box 802
**           Stevens Point, WI 54481
**           USA
**           panther@wctc.net
**
**  To understand pointers, compile and execute this program
*/

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>   // for getch()

char *messages[] = { 
  "\nUnderstanding pointers in C\n",
  "x[1] is shorthand for *(x + 1)\n",
  "After memorizing that fact, pointers are easy!",  
  "Wherever array notation is used, pointer notation",
  "can be substituted.  Two examples appear below:\n" };

  // First, let's declare z as an array of pointers to int
  int z[] = {640, 76, 123, 585, 39}; 
  // Next, let's declare x as an array of pointers to char
  char *x[] = {"Aloha", "Goodbye", "Howdy", "Hello world!", "Hi"};

  
main()
{
  int i;
  int *q;      // declare q as pointer to int 
  char **ptr;  // declare ptr as pointer to pointer to char

  q = z;       // point q to start of array z (same as q = &z[0])
  ptr =  x;    // point ptr to start of array x (same as ptr = &x[0])     	  

  
  for (i = 0; i < 80; i++) printf("\n");      // portable clear screen
  for (i = 0; i < 50; i++) printf("-");       // display some dashes
  for (i = 0; i < 5; i++)  printf("%s\n", *(messages + i) );  

 
  printf("// First, let's declare z as an array of pointers to int");
  printf("\nint z[] = {640, 76, 123, 585, 39}; ");
  printf("\n// Next, let's declare x as an array of pointers to char");
  printf("\nchar *x[] = {\"Aloha\", \"Goodbye\", \"Howdy\", \"Hello world!\", \"Hi\"};\n");

  
  printf("\nchar **ptr;  // declare ptr as pointer to pointer to char");
  printf("\nint *q;      // declare q as pointer to int ");
  printf("\nq = z;       // point q to start of array z (same as q = &z[0])");
  printf("\nptr =  x;    // point ptr to start of array x  \n");     	  

  
  printf("\nExample 1:   *(q + 2) is %d\n", *(q + 2) );      
  printf("\nExample 2:   *(ptr + 3) points to \"%s\"", *(ptr + 3) ); 

    
  printf("\n\nPress any key to to exit [ ]\b\b");     
  fflush(stdout);
  getch();
  exit(0);
}