linux - Can we set the port number for listening in some automatic way rather than hardcoding it? -

in typical example client server programs found on net, can see following hardcoded way of specifying port number process id of process used handle incomming messages.

can set port number listening in automatic way rather hardcoding it? i mean how supposed know port number beforehand?

  serveraddr.sin_family         = af_inet;   /* set port number, using htons function use proper byte order       port number process id of process used      handle incomming messages.   */   serveraddr.sin_port           = htons (7891);   /* set ip address localhost */   serveraddr.sin_addr.s_addr    = inet_addr ("127.0.0.1");   /* set bits of padding field 0 */   memset(serveraddr.sin_zero, '\0', sizeof serveraddr.sin_zero);      /*---- bind address struct socket ----*/   bind(welcomesocket, (struct sockaddr *) &serveraddr, sizeof(serveraddr)); 

if port number dynamically identified during execution process of client, transfer server via interprocess communication. e.g.

i suggest perform following :

1. establish initial connection defined , hardcoded port number()

2. transfer port/process id of client server

3. close initial connection

4. establish wanted connection