&quot;<i>In practice, most platforms and compilers have done the same exact thing with the same &quot;undefined&quot; behavior, that a large body of code relies on that defacto standard.</i>&quot;<p>All compilers <i>on the same platform</i> have done the same exact thing with the same &quot;undefined&quot; behavior.<p>At the moment, all platforms are x86. Previously, all platforms were SPARC, and before that, VAX.