[RFH] A simple way to figure out the number of bits used by a long double

[Tim Prince]

On 2/26/2010 5:44 AM, Ed Smith-Rowland wrote:
> Huh.  I would have *sworn* that sizeof(long double) was 10 not 16 even 
> though we know it was 80 bits.
>
As you indicated before, sizeof gives the amount of memory displaced by 
the object, including padding.  In my experience with gcc, sizeof(long 
double) is likely to be 12 on 32-bit platforms, and 16 on 64-bit 
platforms.  These choices are made to preserve alignment for 32-bit and 
128-bit objects respectively, and to improve performance in the 64-bit 
case, for hardware which doesn't like to straddle cache lines.
It seems the topic would have been more appropriate for gcc-help, if 
related to gcc, or maybe comp.lang.c, if a question about implementation 
in accordance with standard C.

-- 
Tim Prince