[fpc-pascal] How to get the offset of a record

[Mark Morgan Lloyd]

Jonas Maebe wrote:
> On 30 Apr 2011, at 14:30, Rainer Stratmann wrote:
> 
>> In Turbopascal it was possible with offs()
>>
>> type
>> rectype = record
>>  var1 : longint;
>>  var2 : longint;
>>  var3 : boolean;
>> end;
>>
>> var
>> o : longint;
>> recvar : rectype;
>>
>> o := offs( recvar.var1 );  // --> 0
> 
> That's incorrect. In TP, Ofs(recvar.var1) (with one "f") returns the offset in the segment that contains the "recvar" variable. It does not return the relative offset of the field inside the record type.

But in at least some cases Ofs() was normalised to always contain 0..15, 
so it would be easy to (mis)interpret it as an offset into an allocated 
block.

-- 
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]