> because much (most?) code is not written to a strict C or C++ standard, but is "C/C++" and various extensions.

Absolutely true. I generally insist on folks learning C and C++ interoperability before diving in to all the "Modern C or C++" goodness. It helps them in understanding what actually is going on "under the hood" and makes them a better programmer/debugger.

See also the book Advanced C and C++ Compiling by Milan Stevanovic.