Program to find your system type (32bit || 64bit) - http://vivek.techiestuffs.com/2012/find-your-operating-system-32bit-64bit/

find-sys.c

//Program to find the type of operating system 32bit or 64 bit

#include<stdio.h>

void findit(char s[])  // Function which accepts array of characters(String)
{
  int a=sizeof(s);   // Finding the size of s[] which is a pointer
  
  if(a==4)    // checking whether a is 4byte
  printf(" 32bit system\n");
  
  elseif(a==8)  //checking whether a is 8 byte
  
  printf("64bit system \n");
  
  else
  printf("WTF !!!! \n");    // If above two condition doesn't satisfy then  print this line.
}

void main()
{
  findit("a");   // passing "a" to the function findit
}