Question: I'm writing a program that uses QUdpSocket for transmitting data over the network. This is my first socket program, and I've come across an interesting problem called Endianness.

My actual question in, do I have to worry about Endianness when I'm using QNetwork as my sockets library? If I do have to worry, what do I have to do to properly avoid Endianness problems?

Answer: 
Generally, you need to worry about endianness (byte-order) when you transfer integers larger than a single byte from one computer to another. In C/C++, this means that if you're sending something like a 16-bit, 32-bit or 64-bit integer, you need to first convert the integer to *network byte order*, (also known as Big-Endian). The computer on the receiving end must then convert the incoming integers to *host byte order*, which is whatever byte-order the host-machine uses natively. This is usually done using the `htons` and `ntohs` series of library functions, but with the Qt library you can also use the `qToBigEndian` and `qFromBigEndian` functions.

Note that you don't need to worry about endianness when sending ASCII or UTF-8 text, because these formats are composed of sequences of individual bytes, rather than multi-byte data types.
Intel CPUs use little endian. Most everything else is big endian. The default network byte order is big endian.

To test if endianness is a problem, send the value 0x12345678 and check if it makes it as the same or 0x78563412. If the value on the receiving computer is the later value, then the endianness is not the same between the two systems.

Check [this wikipedia article](http://en.wikipedia.org/wiki/Endianness) for info on endianness.