Imperfect C++ Practical Solutions for Real-Life Programming

Part Two. Surviving the Real World

As is the case with C, C++ leaves the definition of a great many of its features open. In the parlance of the standard (C++-98: 1.3), a conformant implementation may have features that are implementation-defined, or are unspecified. Both of these terms mean that such features can be implemented as the compiler vendor deems fit and/or the operating environment mandates. The difference between them is that implementation-defined behavior has to be documented, whereas unspecified behavior does not. For the sake of clarity, I'm going to refer to all of this as implementation defined, since there are precious few unspecified things that you genuinely will not care about. Note that this is quite different from undefined ...