title: Read a file containing 16bit signed data
body: <p>I would like to open a file (approx 400kb) containing 16bit signed data ,  do some computations (for example output[i] = input[i] - input[i-1]),  and then write the output in a new file.</p>
  
  <p>I'm a bit stuck with such a simple thing in C++ : I know how to write text in files, but not raw data.  A small working example would be great!</p>