Sizeof empty struct is 0 byte in C but in C++ it is 1 byte. Why? What's the difference?
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What's the difference? They're different languages. – Mike Seymour Feb 18 '14 at 11:21
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ok! But new features of C is nothing but C++ Correct! if it is different language means how the header files are supported of c in C++? There is a similarity b/w two languages. but why it is 0 byte in C? – Ramakrishna Feb 18 '14 at 11:25
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@Ramakrishna: Simple: not all C header files are supported in C++. – PlasmaHH Feb 18 '14 at 11:51
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In C its not correct, you cannot have a struct without a member in it.
C99 says,
If the struct-declaration-list contains no named members, the behavior is undefined.
However GCC allows you to have a no member struct with size being 0. G++ treats struct as if it has a single member of type char in it.
Look at this previous SO answering why in C++ the size is 1B.
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Clang will also print 1 byte if you apply `sizeof()` in an empty struct (should be same for a class). – gsamaras Apr 13 '19 at 15:39