Donkey

[Henk]

Yesterday I noticed my engine played at least 100 ELO less than before.
I could not figure out why for I hardly changed anything important.

But it was the << operator again


move.Value = capture.Points << 5 - move.Start.Occupier.Points

instead of

move.Value = (capture.Points << 5) - move.Start.Occupier.Points

Actually I had to look up the priority of << operator in C to be sure.

[lucasart]

lol.

we've all made mistakes like that.

use parentheses when in doubt.

[AlvaroBegue]

I suggest you use standard arithmetic operators when possible, because you are less likely to make mistakes and the compiler understands they mean the same thing.

Code: Select all

move.Value = capture.Points * 32 - move.Start.Occupier.Points;

[pocopito]

+1

Parenthesis are your friends

A nice feature I recently found in Clang compiler; it advises you when an expression is kind of ambiguous and suggests the use of parenthesis.

[Henk]

+1

Parenthesis are your friends

A nice feature I recently found in Clang compiler; it advises you when an expression is kind of ambiguous and suggests the use of parenthesis.

Perhaps I was shuffling with code. If you use a = b << c; there is no problem. When you are not careful and add another term a = b << c + d you get the error. Same hold for | and &.

But the main cause is that I'm not used to using << and >> operators.

I also have problems with ?: because I always use if then else

For instance

a && b ? c : d

[stegemma]

I suggest you use standard arithmetic operators when possible, because you are less likely to make mistakes and the compiler understands they mean the same thing.

Code: Select all

move.Value = capture.Points * 32 - move.Start.Occupier.Points;

Yes, and if the compiler is smart enough, sometimes instruction like this can be converted in just one LEA assembly instruction. This assembly instruction can compute very fast formula like "a x b +c", when b is a power of two because it is normally used to calculate address displacements (LEA stay for Load Effective Address). Another advantage is that it uses address logic instead of normal CPU computation logic, giving better performance and processor pipes use.