Question

How can I copy data from an int (int port1 = 52010) to a pair of unsigned chars (unsigned char port2[2]? I don’t know how to deal with the division.

Answer 1

You typically use masking and shifting.

const unsigned short port = 52010;
uint8_t port2[2];

Big-endian:

port2[0] = port >> 8;
port2[1] = port & 255;

little-endian:

port2[0] = port & 255;
port2[1] = port >> 8;

For things like port numbers as used in IP networking, you typically always go to the so-called “network byte order” (aka “big-endian”), and there’s a special macro for doing this:

const unsigned short port_n = ntohs(port);

Note that this keeps the port number as a unsigned short, while swapping the bytes if necessary.