Packing/unpacking binary data in C - doubles, 64 bits

[bruce.labitt at autoliv.com]

gnhlug-discuss-bounces at mail.gnhlug.org wrote on 09/10/2009 10:12:12 PM:

> 
> 
> Ooops - I forgot about the void * ...
> 
> >> Any suggestions to look for a 2^53 type problem?
> >
> >Well, just for fun, how about going back to basics - what does this
> >little program generate on all the systems in question?
> 
> #include "stdio.h"
> 
> main( int   argc,
>       char *argv[] )
> {
>     printf( "sizeof(              double) %2u\n", sizeof( double) );
>     printf( "sizeof(              float)  %2u\n", sizeof( float)  );
>     printf( "sizeof(long          double) %2u\n", sizeof(long double) );
>     printf( "sizeof(long signed   long)   %2u\n", sizeof(long signed 
long)   );
>     printf( "sizeof(long unsigned long)   %2u\n", sizeof(long 
unsignedlong)   );
>     printf( "sizeof(     signed   char)   %2u\n", sizeof(     signed 
char)   );
>     printf( "sizeof(     signed   long)   %2u\n", sizeof(     signed 
long)   );
>     printf( "sizeof(     signed   short)  %2u\n", sizeof(     signed 
short)  );
>     printf( "sizeof(     unsigned char)   %2u\n", sizeof( unsignedchar)  
);
>     printf( "sizeof(     unsigned long)   %2u\n", sizeof( unsignedlong)  
);
>     printf( "sizeof(     unsigned short)  %2u\n", sizeof( unsignedshort) 
 );
>     printf( "sizeof(         void     *)  %2u\n", sizeof(         void
> *)  ); /* Fprgot this one */
> }
> 

Here are the sizes run on the two platforms, both 64 bit OS.  Identical.

                                P4      Cell
double                  8       8
float                           4       4
long double                     16      16
long signed long                8       8
long unsigned long      8       8
signed char                     1       1
signed long                     8       8
signed short            2       2
unsigned char           1       1
unsigned long           8       8
unsigned short          2       2
void *                  8       8

-Bruce

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