Snippet Clarification byte array to port number

Question

I have a byte array that contains 6 bytes last 2 represents the port number while searching for a way two convert these last to bytes to a port number i have come across this snippet,

            int port = 0;
        port |= peerList[i+4] & 0xFF;
        port <<= 8;
        port |= peerList[i+5] & 0xFF;

it works but i need some clarification as to how it works?

Answer 1

  =======================
  |  byte 5  |  byte 6  |
  |----------|----------|
  | 01010101 | 01010101 |
  =======================

Basically, it takes byte #5, shift is 8 bits to the left resulting in 0101010100000000 and then uses the bitwise or operator to put the byte 6 in the place of zeros.

Answer 2

    int port = 0;                       // Start with zero
    port |= peerList[i+4] & 0xFF;       // Assign first byte to port using bitwise or.
    port <<= 8;                         // Shift the bits left by 8 (so the byte from before is on the correct position)
    port |= peerList[i+5] & 0xFF;       // Assign the second, LSB, byte to port.

Answer 3

The code simply takes the last 2 bytes from the array and uses them as a big-endian number.

Usually in network packets the port number is transferred in big-endian (meaning the byte with the lower address is more significant).

The code takes byte number i+4 and uses it as the MSB and byte i+5 as the LSB of the port number.