🚀 go-pugleaf

In article <Pine.SUN.3.91.951010144335.13726A@lagrange.uwaterloo.ca>,
Viet-Trung Luu  <vluu@lagrange.uwaterloo.ca> wrote:
>Well, the cost for checking in C/C++ programs shouldn't be much more than
>for programs written in other languages. Is that an indication of how 
>slow other languages are or are you saying that C/C++ programs are 
>unchecked because those who use C/C++ want small fast programs?

No, I don't think it's true (that checking in C/C++ is the same as in
other languages).  For example, in C, a variable declared as
pointer-to-something might be the sort of pointer that links through
heap objects (a linked list, or whatever), or it might be the sort of
pointer that steps through an array.  It's very difficult (and in the
general case, impossible), to tell which is which.  So, for a C compiler
to check array bounds, it has to include several words of extra dope
with every pointer, just in case it *might* be the sort that steps
through an array.  Other languages (e.g., Ada, Pascal, etc) make this
bounds-checking much simpler, and much more efficient.

>(Obviously, it is more difficult and thus "costly" to check C/C++ 
>programs, but not so much more than for other languages. I guess most of 
>the cost is due to the freedom that C/C++ allow.)

But is that "freedom" useful?  If you know ahead of time that you're
indexing into an array, why not tell the compiler (or bounds-checking
tool)?

- Bob