Author: Dieter Buerssner
Date: 14:53:20 09/24/03
Go up one level in this thread
On September 24, 2003 at 07:43:33, Uri Blass wrote:
>I was told that unsigned varaibles are better to use in every case that I can do
>it.
Perhaps, you misunderstood. I think, one should use unsigned, for things, where
one is likely to do some bit-operations. For example some flags variable:
if (flags & THIS_CONDITION)
Or more important shifts:
some_condition = x >> some_shift;
Here using a signed integral type can easily yield in an error. Hash-keys,
bitboards, etc. all seem to call for an unsigned type.
>one of the varaibles that cannot get negative value is the ply of the search but
>the problem is that this varaible is connected with beta because I tell movei
>always that beta cannot be more than 9999-ply
I think, a signed integral type is a natural choice for ply.
>How do you solve that problem?
>
>practically I was too lazy to replace all my varaibles and decided only to
>replace few varaibles and remember that rule for new varaibles.
>
>It was another varaible that I defined as unsigned and was connected with ply
>and when I got the warning
>signed/unsigned mismatch I tried to change ply to be unsigned and got more
>warning of the same kind because beta is unsigned.
>
>I can get rid of the warning by adding signed.
>
>if (beta>9999-(signed)ply)
> beta=9999-(signed)ply;
I suggest, to not use the cast. Such casts can easily hide errors, while the
code without the cast is fine.
Perhaps not in this particular case, but assume something like:
int foo(int a, unsigned int b)
{
return a - b; /* just as an example */
}
No, assume you changed your program, and you recognized, that you need wider
types for the return value and for b (a is still fine as int). Say you want
INT64 foo(int a, UINT64 b)
{
return a - b; /* will still work */
}
With the cast:
INT64 foo(int a, UINT64 b)
{
return a - (signed)b; /* Oops, no warning, but probably wrong */
}
>I doubt if it is a good idea and it is possible that the conversion is going to
>cost time for the computer.
In practice, extremely unlikely (on 2 complemt's computers).
Regards,
Dieter
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