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???
05/23/05 06:06
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#93727 - Platform-dependence
Responding to: ???'s previous message
Michael Karas said:
Do note that the scheme on another platform may require a different coding if a long were an 8-byte number or if the stored order of bytes was different.

This is of fundamental impotance when using unions in this way!

You should assume that a different coding will be required on a different platform, until proven otherwise.
The key issues to consider are:
  • Sizes of the data types; eg, is an int 16 or 32 bits;
  • Byte-order within multi-byte values; ie, Big- or Little Endian;
  • Whether any "padding" bytes are added between elements by the compiler.

    Note that even different compilers on the same target processor may use different schemes!




  • List of 27 messages in thread
    TopicAuthorDate
    Unions in C            01/01/70 00:00      
       You miss the point completely...            01/01/70 00:00      
       Easy with Union            01/01/70 00:00      
          You can see from the Raghu example...            01/01/70 00:00      
             Platform-dependence            01/01/70 00:00      
                Padding in unions            01/01/70 00:00      
                   portability            01/01/70 00:00      
          array=pointer...?            01/01/70 00:00      
             array != pointer            01/01/70 00:00      
             Quirk of C            01/01/70 00:00      
                Read the FAQ            01/01/70 00:00      
                   Read the Comment            01/01/70 00:00      
                      Read everything            01/01/70 00:00      
                         Looks the same to me            01/01/70 00:00      
                            This One            01/01/70 00:00      
                            That's the problem            01/01/70 00:00      
                               Good example            01/01/70 00:00      
                                  No fun            01/01/70 00:00      
                                     Well...            01/01/70 00:00      
                                     Of course it does!            01/01/70 00:00      
                                        Hmm            01/01/70 00:00      
                            Actually, even less.            01/01/70 00:00      
                               const pointer            01/01/70 00:00      
       O.K you win            01/01/70 00:00      
          Please conclude            01/01/70 00:00      
             Not Exactly            01/01/70 00:00      
             End of wrong stick?            01/01/70 00:00      

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