Re: Is Linux Unix?
Jeronimo Pellegrini <firstname.lastname@example.org> wrote in message news:<2ox9Qemail@example.com>...
> > There's another problem with the above C++ code: If ny and nz
> > aren't constant, you can't write
> > double s[ny][nz];
> > Instead, either you allocate the array in two stages:
> > double** s = new (double*)[ny];
> > for (j=0; j < ny; ++j) s[j] = new double[nz];
> Actually, the first version works -- and both C and C++ (tested here with
> gcc -- not sure it it became a standard or not)) will dynamically allocate
> memory for you. Try this:
> int size1, size2, i, j;
> cin >> size1;
> cin >> size2;
> double vec[size1][size2];
Wow, that's news to me! The first ANSI C++ standard (1997 or 1998) doesn't
allow it. "The number of elements of the array, the array bound, must be
a constant expression. . . ." (Stroustrup, _The C++ Programming Language_,
3rd ed., p.89. Although this book isn't the standard document itself,
I don't expect that there would be such a big difference as this.)
And, certainly, neither size1 or size2 above is a constant expression.
I don't know whether the C++ standard has been revised since.
If this feature is or become standard or de facto standard, that's a step
forward for numerical computations.
Thanks for the info,