Berkeley CSUA MOTD:Entry 34697
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2025/05/24 [General] UID:1000 Activity:popular
5/24    

2004/11/5-7 [Computer/SW/Languages/C_Cplusplus] UID:34697 Activity:high
11/5    In C, why is the "offsetof" macro defined to be of type size_t but not
        ptrdiff_t?  Thx.
        \_ Probably because ptrdiff_t is signed and size_t isn't.
           \_ How does being signed make ptrdiff_t less portable?
              \_ Imagine a 16-bit C implementation, where int is 16 bits, long
                 is 32 bits, and the maximum object size is 64k - 1.  size_t
                 can be unsigned int, but ptrdiff_t has to be long; you save
                 time and memory by using size_t when possible.  --mconst
              \_ Who said anything about portability?  It looks like one of
                 those cases where since the value is always >= 0 the standards
                 guys use an unsigned type.
2025/05/24 [General] UID:1000 Activity:popular
5/24    

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