Hello,
I am having a hard time to write a simple function that determines if a
Double value is Int64:
function IsInt64(const aNumber: Double): Boolean;
I know about precision problems. I basically want to know if
Round(aNumber) overflows.
In Delphi, Round() doesn't throw an exception if the value exceeds Int64
range, so it is safe to compare SameValue(aNumber, Round(aNumber)):
function OXmlIsInt64(const aNumber: Double): Boolean;
begin
Result := not IsNan(aNumber) and not IsInfinite(aNumber) and
SameValue(Frac(aNumber), 0) and SameValue(aNumber, Round(aNumber));
end;
That's OK for me.
But in FPC, I get:
Project TestProject raised exception class 'External: FLT INVALID OPERATION'
in Round().
Is there a chance to not throw this exception? I expect this problem so
I don't want to do something like:
function OXmlIsInt64(const aNumber: Double): Boolean;
begin
try
Result := not IsNan(aNumber) and not IsInfinite(aNumber) and
SameValue(Frac(aNumber), 0) and SameValue(aNumber, Round(aNumber));
except
Result := False;
end;
end;
I tried to switch overflow checks off:
{$OVERFLOWCHECKS OFF}
But obviously it doesn't help (it's a different exception).
----
I'd really like to get rid of the try-except block... It's the same with
StrToInt() vs TryStrToInt(). IMO there should be a possibility to catch
expected errors without exceptions.
Any ideas?
Thanks
Ondrej
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