title: 0xDEADBEEF equivalent for 64-bit development?
body: <p>For C++ development for 32-bit systems (be it Linux, <a href="http://en.wikipedia.org/wiki/Mac_OS" rel="noreferrer">Mac OS</a> or 
  Windows, <a href="http://en.wikipedia.org/wiki/PowerPC" rel="noreferrer"><code>PowerPC</code></a> or x86) I have initialised pointers that 
  would otherwise be undefined (e.g. they can not immediately 
  get a proper value) like so:</p>
  
  <pre><code>int *pInt = reinterpret_cast&lt;int *&gt;(0xDEADBEEF);
  </code></pre>
  
  <p>(To save typing and being <a href="http://en.wikipedia.org/wiki/Don%27t_repeat_yourself" rel="noreferrer">DRY</a> the right-hand side would normally 
  be in a constant, e.g. BAD_PTR.)</p>
  
  <p>If pInt is dereferenced before it gets a proper value then 
  it will crash immediately on most systems (instead of 
  crashing much later when some memory is overwritten or going 
  into a very long loop).</p>
  
  <p>Of course the behavior is dependent on the underlying 
  hardware (getting a 4 byte integer from the odd 
  address 0xDEADBEEF from a user process may be perfectly 
  valid), but the crashing has been 100% reliable for all the 
  systems I have developed for so far (Mac OS <a href="http://en.wikipedia.org/wiki/Motorola_68000_family" rel="noreferrer">68xxx</a>, Mac OS 
  PowerPC, Linux Redhat Pentium, Windows GUI Pentium, Windows 
  console Pentium). For instance on PowerPC it is illegal (bus 
  fault) to fetch a 4 byte integer from an odd address.</p>
  
  <p>What is a good value for this on 64-bit systems?</p>