> C++ code I wrote 15 years ago won't compile today

Do you recall specifically why?

Also, isn't C pretty 'time proof'? The only time I've seen old C fail to compile was when dealing with a real relic of a codebase. If memory serves it used the pre-standardisation parameter-declaration syntax:

    void my_func(x, y)
    {
        int x;
        long y;
    }