title: Variable-length std::array like
body: <p>As my usually used C++ compilers allow variable-length arrays (e.g. arrays depending on runtime size), I wonder if there is something like <code>std::array</code> with variable size? Of course <code>std::vector</code> is of variable size, but it allocates on heap, and reallocates on need.</p>
  <p>I like to have a stack allocated array with size defined at runtime. Is there any <code>std</code>-template that may feature this? Maybe using <code>std::vector</code> with a fixed maximum size?</p>