Re: sizeof() struct w/ nested enum returns wrong size

From:
"Ben Voigt [C++ MVP]" <rbv@nospam.nospam>
Newsgroups:
microsoft.public.vc.language
Date:
Wed, 16 Apr 2008 10:58:12 -0500
Message-ID:
<OGsCCp9nIHA.4832@TK2MSFTNGP02.phx.gbl>
homerjsimpson742@live.com wrote:

I have the following situation compiling using Visual Studio 2003:

#include "stdafx.h"
#include <iostream>
#include <limits>

namespace Outer{
     class Xyz {
     public:

           typedef struct {
                 enum { classConstant1 = 0x0001,
                             classConstant2 = 0x0002,
                             ForceSize2Bytes = 0x7FFF
                 }; // end enum
           } Constants; // end struct

     }; // end class Xyz

} // end namespace Outer

int _tmain(int argc, _TCHAR* argv[])
{
     std::cout << "The sizeof() Outer::Xyz::Constants = "
                   << sizeof(Outer::Xyz::Constants)
                   << std::endl;
     std::cout << "Outer::Xyz::Constants::ForceSize2Bytes = 0x"
                   << std::hex
                   << Outer::Xyz::Constants::ForceSize2Bytes
                   << std::endl;

     std::cin.ignore((std::numeric_limits<std::streamsize>::max()),
'\n');

     return 0;
} // end main()

Here's the output:

The sizeof() Outer::Xyz::Constants = 1
Outer::Xyz::Constants::ForceSize2Bytes = 0x7fff

The struct size is reported as one while the cosntants clearly output
a 2 byte value.

Does anyone knwo what's going one?


sizeof(Outer::Xyz::Constants) is the size of an *instance* of type
Constants, not the size of the static data.

Thanks, HJS

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