How to write endian agnostic C/C++ code?

c++ c endianness
d33tah picture d33tah · Dec 21, 2012 · Viewed 19.2k times · Source

I did some googling and couldn't find any good article on this question. What should I watch out for when implementing an app that I want to be endian-agnostic?

Answer

Carl Norum picture Carl Norum · Dec 21, 2012

The only time you have to care about endianness is when you're transferring endian-sensitive binary data (that is, not text) between systems that might not have the same endianness. The normal solution is to use "network byte order" (AKA big-endian) to transfer data, and then swizzle the bytes if necessary on the other end.

To convert from host to network byte order, use htons(3) and htonl(3). To convert back, use ntohl(3) and ntohs(3). Check out the man page for everything you need to know. For 64-bit data, this question and answer will be helpful.

Related questions

C/C++: Force Bit Field Order and Alignment

I read that the order of bit fields within a struct is platform specific. What about if I use different compiler-specific packing options, will this guarantee data is stored in the proper order as they are written? For example: struct …

Read More
Converting a UINT32 value into a UINT8 array[4]

My question is how do you convert a UINT32 value to a UINT8 array[4] (C/C++) preferably in a manner independent of endianness? Additionally, how would you reconstruct the UINT32 value from the UINT8 array[4], to get back to where …

Read More
Is there a way to enforce specific endianness for a C or C++ struct?

I've seen a few questions and answers regarding to the endianness of structs, but they were about detecting the endianness of a system, or converting data between the two different endianness. What I would like to now, however, if there …

Read More