Sometimes the hardware can present you with a conflicting choice of the "correct" size for a chunk of data. Consider a piece of hardware that has a 4 KB memory window. If the hardware brings various data structures into view with that window, it's impossible to determine a priori what the data size should be for a particular element of the window. Is it a 32-bit long integer? An 8-bit character? Blindly performing operations as in the above code sample will land you in trouble, because the CPU will determine what it believes to be the correct endianness, regardless of what the hardware manifests.