Essentially, an arithmetic overflow is happening. Since the largest
Int64 possible is 9,223,372,036,853,775,807, going one above that (the
result to abs(low(int64))) wraps back around to -9,223,372,036,853,775,808.
Internally, you can think about negating (positing?) a negative number
as inverting the bits and then adding one (aka. two's complement), so
low(int64) is 1000...000, which inverted becomes 0111...111, and then
adding one results in 1000...000 again.
Kit
On 04/04/2024 14:14, Martin Frb via fpc-devel wrote:
The below writes: -9223372036854775808
Shouldn't absolute return a positive number?
program Project1;
begin
writeln( abs(low(int64)) );
end.
Seems
writeln( abs(low(longint)) );
also returns negative...
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