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I think this is the way easier way to tell if the stack is growing upwards or downwards...
Idea--
1. I am declaring a variable in main function and storing it's address
2. Then i call a function from main and declare a variable there store this address in another variable.
3. Based on the values of addresses i can easily tell whether the stack is growing upwards or downwards.

#include<stdio.h>		
#include<string.h>
#include<stdlib.h>
#include<math.h>
#include<unistd.h>


int func()
{
	int p=0;
	return (&p);
}
int main()
{
	int i=9;
	int x=&i;
	int y=func();
	if(x>y)
		printf("Downward\n");
	else
		printf("Upward\n");
       return 0;
}

stack and heap are memory used for allocation by programs. A program has:
1. code
2. heap
3. stack
4. BSS
5. data (global and static data)

stack is used for storage of auto variables in program. When a program starts in main() all the auto variables are stored in stack using LIFO algo. Stack can grow down or UP depending on the system being used.

example code taken from other site :)

debug this program and see how memory is being allocated, this will give you a fare understanding of how stack works.

This program will give error, because in "fn()" we eat up the memory assigned to "i" and when fn() finishes that memory is freed. But we try to print "i' which has already been freed.

#include <iostream>
using namespace std;

void fn(void)
{
    int * ptr;
    ptr = (int *)&ptr;
    ++ptr;
    int* mainfp = (int*)(*ptr);
    --mainfp;
    --mainfp;
     *mainfp = 20;
    return;
  }

int main (void)
{
   int i = 10;
   fn();
   cout<<”I =<<i<<endl;
   return 0;
}

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

int *recursive(int x){
        int y=0;
        if(x==1)
            return &y;
        int *res = recursive(x-1);
        if((res-&y)>0)

printf("Stack is growing towards higher address\n");
        else
        printf("Stack is growing towards lower address\n");                             }

int main(){
        recursive(3);
}

void function f()
{
int p=0, q=0;
int *add_p =NULL, *add_q=NULL;

add_p = &p;
add_q = &q;

if(add_p > add_q) {
/* p higher on stack */
printf("Downward growing");
} else {
printf("Upward growing");
}

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

int *recursive(int x){
int y=0;
if(x==1)
return &y;
int *res = recursive(x-1);
if((res-&y)>0)

printf("Stack is growing towards higher address\n");
else
printf("Stack is growing towards lower address\n");
}

int main(){
recursive(3);
}