On Tue, Feb 22, 2011 at 12:34 AM, prabhu <prabhum@xxxxxxxxxxxxx> wrote: > Jose Celestino wrote: > > On Seg, 2011-02-21 at 21:41 +0530, prabhu wrote: > > > Hi all, > > Could anyone please explain the use sin_zero in sockaddr_in? > > > > Padding to allow for casting. > > > > Hi Jose, > > Could u please elaborate little more... why we need this 8 byte padding. > > My complete Question: > 1. Actually total size of sockaddr_in is 16 byte and out of 16 byte why we > have to use 8 byte for padding.? > 2. Do we use these 8 byte for any other usage for real time? Unix network programming chapter 3.2 says that, "The POSIX specification requires only three members in the structure: sin_family, sin_addr, and sin_port. It is acceptable for a POSIX-compliant implementation to define additional structure members, and this is normal for an Internet socket address structure. Almost all implementations add the sin_zero member so that all socket address structures are at least 16 bytes in size. " It's kinda like structure padding, maybe reserved for extra fields in the future. You will never use it, just as commented. -- Wick MSN/GTalk: izhangxc[AT]gmail.com _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
