/*
Program to demonstrate pointers (integers)
Version 1.0 / 2001.09.01.
Peter Schindler pstrainer@gmx.net
*/

#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

/* Declaration of globals ***********************************/
void suba (int m);
void subb (int *pm);	//	*pm is a pointer to int

/* Main program *********************************************/
void main (void){
int i,j,k;				// integer variables
int *pi;				// pointer to int variable

printf("Pointer Test Program\n");
printf("Enter integer number: ");
scanf("%d",&i);
printf("\n");

// set pointer pi to the address of i ("let it point at i")
pi=&i;

/* assign other variables in different ways			*/
j=i;		//   set j to value of i
k=*pi;		//   set k to value of whatever pi points at

/* send VALUE to subroutine						*/
printf("main01 i=%d j=%d k=%d pi=%d\n",i,j,k,pi);
suba(i);	//	i remains unchanged
printf("main02 i=%d j=%d k=%d pi=%d\n\n",i,j,k,pi);

/* send POINTER to subroutine					*/
printf("main03 i=%d j=%d k=%d pi=%d\n",i,j,k,pi);
subb(pi);	//	i can be changed
printf("main04 i=%d j=%d k=%d pi=%d\n\n",i,j,k,pi);

printf("End of program\n");
_getch();
}

/*  suba: get integer value and change it *******************
    You may change local variable, without effect to main   */
void suba (int m) {
int n;
n=m;
printf("suba01 m=%d n=%d\n",m,n);
m++;     /* change local variable                           */
printf("suba02 m=%d n=%d\n",m,n);
}

/*  suba: get pointer value, change value *******************
    You may change local variable but also main !           */
void subb (int *pm) {
int m,n;
m=*pm;   /* set m to whatever pm points at                  */
n=m;
printf("subb01 m=%d n=%d pm=%d\n",m,n,pm);
m++;     /* change local variable                           */
*pm=m;   /* set whatever pm points at to m                  */
printf("subb02 m=%d n=%d pm=%d\n",m,n,pm);
}

/* eof ******************************************************/