Hash table question

[XodoX]

I have a few questions. Server-client code with a (distributed) hash table. Give the peers their own port, own node-ID, predecessor and successor ( node-ID, IP and port of them).

That's a snippet of it.

port= argv[1];
    ownNodeID = atoi(argv[2]);
    sucNodeID = atoi(argv[3]);
    sucIP = argv[4];
    sucPort = argv[5];
    preNodeID = atoi(argv[6]);
    preIP = argv[7];
    prePort = argv[8];
    int sizeOfHashTable = (ownNodeID > preNodeID)? ownNodeID-preNodeID : preNodeID-ownNodeID;
    entry hashtable[sizeOfHashTable];
    for(i=0;i<sizeOfHashTable-1;i++){
        hashtable[i].occupied=0;
        hashtable[i].key=0;
        hashtable[i].value=0;
    }
    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_DGRAM;
    hints.ai_flags = AI_PASSIVE;

So the first line takes are of the port. But why argv[1] ? Then all the suc, pre etc. So it also takes care of the predecessors and successors, right ? Then it defines the hash table.
But can someone please explain the snippet in a little more detail? And why do you use atoi and argv here?