title: Declaring an octuple precision floating point variable in C++
body: <p>I wish to declare a floating point variable that can store more significant digits than the more common doubles and long doubles, preferably something like an octuple (256 bits), that (I believe) might give about 70 significant digits.</p>
  
  <p>How do I declare such a variable? And will cross-platform compability be an issue (as opposed to fixed-width integers)?</p>
  
  <p>Any help is much appreciated.</p>