Subj : Re: Math error ??? doen't make sense!
To   : borland.public.cpp.borlandcpp
From : maeder
Date : Fri Jul 02 2004 08:36 am

"Stan DeGroff" <sdegroff@bright.net> writes:

> I Programmed in Assembly, Fortran, DbaseIV, MS Prof Basic pre-Win for many
> years.
> This new stuff is mind blowing. So.. I ask for your patient help.
>
> I am using the Sam's Learning C in 24hr book that came with my new
> Bc++ 5.02 compiler.   (I need to learn it from ground up.)
> Reason for using old software is simple. I need to target 16bit embedded
> computer.
>
> Ch 9 Exercise 3
> -------------------
>
> #include<stdio.h>
> #include<math.h>
> main()

While your compiler may accept this, it's not correct. The return value
of each function has to be explicitly given, as in:

int main()


> {
> int x,y;
> long int z;
>
> x=7000;
> y=12000;
> z=x*y;
>
> printf("x * y == %lu\n",z);

Welcome to the world of *printf format string intricacies!

%lu tells the printf engine to expect an unsigned long, but you are passing
it a (signed!) long. What do you get if you change %lu to %ld (or %li, if you
prefer)?

If you don't get the expected result, chances are that long int is too
small to hold the result of the above multiplication. I don't remember how
large a long int was on Borland C++ 5.02 in 16bit programs. What do you
get if you do:

int main()
{
  printf("%u\n",sizeof(long));
}

?

.