Re: How to delete charcters in a string?

[Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>]

"David Thompson" <david.thompson1@worldnet.att.net> writes:

> Pascal Obry <p.obry@wanadoo.fr> wrote :
> >
> > Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov> writes:
> >
> > > tmoran@acm.org writes:
> ...
> > > >   How would you delete a character from a C string?  Seems to me that's
> > > > probably harder that with an Ada string (lack of slice assignment),
> > >
> > > char *S1 = "ABCDEF";
> > >
> > > strncpy (S1 + 3, S1 + 4, 3);
> > >
> > > result in *S1 is "ABDEF".
> > >
> No it's not.  All C arrays, including strings, are zero-origin,
> so _if_ this worked it would produce ABCEF.  But:

Ok. Never post code that hasn't been run, even if it is C :).

> 1) you can't legally modify (store to) a string literal value.
> _Some_ implementations put them in readonly storage and this will
> fault. _Some_ implementations share storage for
> identical(ly-suffixed) values, 

Right. I should have added an extra strcpy to a variable.

> Note char foo[] = "ABCDEF" is different.  That allocates
> space and _initializes_ it by copying the literal value --
> at least notionally, for static-duration variables the copy
> is often embedded in process creation -- and it can then
> be legally modified; but see next.

Hmm. I guess this is a case where array is _not_ defined in terms of
pointer. I had not noticed that before. Guess I can learn stuff even
about C still :).

> > > No where near as pretty or readable as Ada, but just as short and
> > > easy. And I've probably got the "src" and "dest" parameters swapped.
> > > Man, I hate C :).
> >
> Actually (dest,src,len) is the only part you got right.
> I decline to guess what if anything this signifies.

Me too :).

-- 
-- Stephe