title: Ensuring C++ doubles are 64 bits
body: <p>In my C++ program, I need to pull a 64 bit float from an external byte sequence. Is there some way to ensure, at compile-time, that doubles are 64 bits? Is there some other type I should use to store the data instead?</p>
  
  <p>Edit: If you're reading this and <em>actually</em> looking for a way to ensure storage in the IEEE 754 format, have a look at Adam Rosenfield's answer below.</p>