title: Zeroing memory used by STL containers
body: <p>I'd like to use STL containers (plus <code>std::basic_string</code>) to temporarily store keys or passwords in memory, and I'd like to zero the memory when done.</p>
  
  <p>I was initially planning to use STL containers parameterized on a custom allocator that zeroes memory in <code>allocator::deallocate</code>, but I'm presuming that containers are allowed to use memory that doesn't come from the specified allocator.  For example, it seems reasonable for a <code>std::vector</code> or a <code>std::string</code> to contain a fixed-size array member meant for small allocations.</p>
  
  <p>Am I rightly concerned, and should I (sigh) write my own container?</p>