[Freeciv-Dev] Re: (offtopic) C subscripts

[Dirk Stoecker <stoecker@xxxxxxxxxxxxxx>]

Hi,

> > int
> > main (int argc, char *argv[])
> > {
> >   printf("The third letter of the alphabet is %c.\n", 2["ABC"]);
> > }
> 
> Not sure if you're right though... I think some people are going odd on

He is right and compilers do not give a warning on this  :-(

> the thing about pointer arithmetic/subscripts... given that an array
> name and a pointer are the same thing, you get the same results,
> excepting location in memory, with (excuse C++ code, point is the same
> in C)
> 
> char* p = new char[50];

You misunderstood the point: Lets change this line to 2 new lines:
char *a = new char[100];
char *p = a + 20;

> //initialise array
> cout << p[20];
> cout << *(p+20);
> 
> and both should give unexpected results (or possibly errors) with
> 
> cout << p[-1];
> 
> as with
> 
> cout << *(p-1);

Although we use negative subscripts now, we access valid array entries and
don't cause segfaults.

> Sory if someone else said this, or if I misunderstood... I'm a little
> behind, a little out of practise, and a little tired...

Negative offsets are really ugly and I always try to avoid them, but it is
not always possible.

Ciao
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