how in the second case it is 12?????....can u tell the clear expl..
On Wed, Feb 29, 2012 at 8:39 AM, Gene <[email protected]> wrote: > This depends on the compiler and even on the options you give the > compiler. The C nor C++ standards don't say. > > So the asker of the question hasn't give you enough information. > > If you assume 32-bit x86 gcc with no packing options or pragmas, I > think shorts (which are 2 bytes long) are aligned on 2-byte > boundaries. Longs and ints (both 4 bytes long) are on 4-byte > boundaries. Chars (1 byte) can go anywhere. If you follow these > rules, then the first will be laid out: > > Field @ Offset > > a @ 0 // next 3 bytes are padding to reach next 4-byte boundard > b @ 4 > c @ 8 // next 2 bytes are padding > d @ 12 > > so the struct will be 16 bytes in size (a long is 4 bytes). > > In the second case you'll have > > a @ 0 // next 1 byte are padding > b @ 2 > c @ 4 // next 3 bytes are padding > d @ 8 > > so the struct will be 12 bytes in size. > > Even if you are using a 64-bit gcc (without the -m32 flag), you'll get > an entirely different answer! > > > On Feb 29, 11:13 am, Decipher <[email protected]> wrote: > > I need some help in understanding how padding works ?? > > Please answer the following questions with proper explanations.. > > > > struct mystruct1 > > { > > char a; > > int b; > > short c; > > long d; > > > > }; > > > > struct mystruct2 > > { > > char a; > > short b; > > char c; > > long d; > > > > }; > > > > What's the sizeof above 2 structures and why ?? > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/algogeeks?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
