Re: Size of structs containing unions

From: Martin Ambuhl <mambuhl@xxxxxxxxxxxxx>
Date: Fri, 30 Sep 2005 16:09:41 GMT

luke wrote:

hi,
in Visula C++ 6.0 I have declared a struct like this:

typedef struct  _WRITE_INPUT {

    ULONG   DeviceNumber;
    ULONG   RegisterNumber;
    union   {
        USHORT  ShortData;
        UCHAR   CharData;
    };
}   WRITE_INPUT;

I can't understand why, sizeof(WRITE_INPUT) returns 12. It should
return 10, shouldn't it?


Please check the FAQ before posting.
You might find <http://www.eskimo.com/~scs/C-faq/q2.13.html> enlightening.

BTW: Avoid nonstandard typenames in postings. If ULONG, USHORT, and UCHAR are in fact unsigned long, unsigned short, and unsigned char, why not use the real typenames? .

References:
- Size of structs containing unions
  - From: luke

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