// This program uses pointers and pointer arithmetics in C to determine
// if the program is running on a machine with a network byte ordering
// (big endian) or intel byte ordering (little endian).

#include<stdio.h>

int ordering() 
{ unsigned int x = 1;
  return *((char*)&x+3);
} // returns 1 if "big endian" and 0 if "little endian"

int main()
{
  if (ordering()) printf("network byte ordering\n");
  else printf("intel byte ordering\n");
  exit(0);
}


// function to switch the byte ordering of a 32bit integer:
int switchorder(int x)
{
  unsigned char A[4]; 
  A[3] = *((unsigned char*)x);
  A[2] = *((unsigned char*)x+1);  
  A[1] = *((unsigned char*)x+2);    
  A[0] = *((unsigned char*)x+3);  
  return *((int*)A);
}

//  Conceptually speaking, this program uses a non-type safe feature,
//  but in this style of programming we are concerned about the format
//  of data at a low level, and not about what the data represents at 
//  the application level.