Creates a client handle and returns its address.
    Format
      #include  <rpc/rpc.h>
      CLIENT  *clnt_create(char *host, u_long prognum, u_long
              versnum, char *protocol);

1  –  Arguments

 host
    A pointer to the name of the remote host.
 prognum
    The program number associated with the remote procedure.
 versnum
    The version number associated with the remote procedure.
 protocol
    A pointer to a string containing the name of the protocol for
    transmitting and receiving RPC messages. Specify either tcp or
    udp.

2  –  Description

    The clnt_create routine creates an RPC client handle for prognum.
    An RPC client handle is a structure containing information about
    the RPC client. The client can use the UDP or TCP transport
    protocol.

    This routine uses the Portmapper. You cannot control the local
    port.

    The default sizes of the send and receive buffers are 8800 bytes
    for the UDP transport, and 4000 bytes for the TCP transport. The
    retry time for the UDP transport is five seconds.

    Use the clnt_create routine instead of the callrpc or clnt_
    broadcast routines if you want to use one of the following:
    o  The TCP transport
    o  A non-null authentication
    o  More than one active client at the same time

    You can also use the clnttcp_create routine to use the TCP
    protocol, or the clntudp_create routine to use the UDP protocol.

    The clnt_create routine uses the global variable rpc_createerr.
    rpc_createerr is a structure that contains the most recent
    service creation error. Use rpc_createerrif you want the client
    program to handle the error. The value of rpc_createerr is set by
    any RPC client creation routine that does not succeed.

                                   NOTE
       If the requested program is available on the host but the
       program does not support the requested version number, this
       routine still succeeds. A subsequent call to the clnt_call
       routine will discover the version mismatch. Use the clnt_
       create_vers routine if you want to avoid this condition.

3  –  Return Values

    CLIENT *           Client handle containing the server
                       information.
    NULL               Error occurred while creating the client
                       handle. Use the clnt_pcreateerror or clnt_
                       spcreateerror routine to obtain diagnostic
                       information.