Re: Ada BIND was: Improving Ada's image - Was: 7E7 Flight Controls Electronics

["Alexander E. Kopilovich" <aek@VB1162.spb.edu>]

Hyman Rosen wrote:

> >   Check the length of the string to be read, then read either that 
> > number of characters or the maximum buffer size.  Of course, this means 
> > in many cases you have to read the string twice while Ada allows you to 
> > read it once.  (Ask for N characters and get a count of how many you get.)
>
> Huh? fread, fgets, istream.getline, istream.read are all ways of
> reading up to a pre-determined amount of data into a buffer in C
> and C++. In no case does the string need to be read twice.
> What a bizarre claim!

Well, for C, that is for fread and fgets I would say that although these
functions indeed have maximum amount of bytes to be read onto a buffer as
a parameter, but:

1) this maximum, if not computed from "preliminary read", is usually set
manually, it does not computed automatically from the length of the buffer
used in that fread/fgets; therefore there is an obsvious possibility of
programmer's mistake, which will not be noticed by compiler;

2) sometimes there is no reasonable estimate for *guaranteed* maximum of
a string to be read, and therefore the length of the string can be greater
than already allocated buffer; reading a string in chunks can be inconvenient
for some reasons, and thus that double reading (first pass for determining
the length of string, then allocating the buffer, and then second pass with
filling the buffer).

So I find that claim far from bizarre, but rather practical. (Certainly in C++
it is possible to coordinate reading with the buffer size automatically, so I
don't speak about C++ here.)




Alexander Kopilovich                      aek@vib.usr.pu.ru
Saint-Petersburg
Russia