Just a little routine I whipped up to check if the system the code runs on is LittleEndian or not (now there ain't much BigEndian systems anymore as far as I know, but they are still there, I guess).

CheckEndian.cpp

#define Test_EndianCheck
typedef union {
  unsigned char b[4];
  int i;
} ucheck;

namespace TrickyUnits{
  bool IsLittleEndian(){
    ucheck chk;
    chk.i=256;
    return chk.b[1]==1;
  }

  bool IsBigEndian() { return !IsLittleEndian();}
}


#ifdef Test_EndianCheck
#include <iostream>
using namespace TrickyUnits;

int main(){
  if (IsLittleEndian())
    std::cout << "System is LittleEndian\n";
  else
    std::cout << "System is BigEndian\n";
}

#endif