On 14 Jan 2013, at 14:54, ik wrote:
On Mon, Jan 14, 2013 at 3:11 PM, Martin <laza...@mfriebe.de> wrote:
Having recently asked about and learned that it is mainly a hint
about
performance. I have now another question about this hint:
project1.lpr(6,9) Hint: Mixing signed expressions and longwords
gives a
64bit result
Actually not so much about the hint, as about the fact that in the
below
example fpc extends the operands to 64 bits.
program Project1;
var
x: cardinal;
i, j: integer;
begin
i:= x or j
end.
I understand the need for a 64 bit operation for +/-/</>/*/...
But the "or" operator works bitwise, it does not treat the operands
as
numbers which could either be signed or unsigned? Or does it? If it
does
not, why does it need to use 64 bit?
i is an "integer" type, and you try to assign it a number that might
have 64 bit value.
It might overflow the memory itself.
And as an addendum to my previous mail, related to the above: in case
range checking is on, then the widening will not be removed and the
full (signed) 64 bit value will be range checked against the type of
the variable to which the result is assigned.
Jonas
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