Checking whether the client is connected to the Server

[micro]

Hi,
I am working on establishing Client-Server module over TCP.I have put a se
up such that my PC acts as a normal server where I can connect it from som
other PC's on my LAN using 'telnet ipaddress port' command and once I ge
connected with the server and can give some input from client computer s
that it gets displayed on my server window(connection is established an
data exchange takes place).
Until here I can say that the server is working fine and what i wanted t
implement is that now I wrote a code using lwIP API for the Altiu
Nanaboard so that my NB3000 acts like a client and i wanted it to ge
connected to my PC Server.
Here goes my code for the client part which gets connected to the Serve
with given IPaddress.

int tcp_client(void)
{
char data[] = "Hello World";
struct netconn *conn;
struct ip_addr ServAddr;
err_t err;
u16_t port;

port = 7777;

conn = netconn_new(NETCONN_TCP);

IP4_ADDR(&ServAddr, 192,168,xx,xxx);

err = netconn_connect(conn, &ServAddr, port);

printf("err = %d", err); // here I am getting err = -4 as output when
print it.

if(err == ERR_OK)

netconn_write(conn, data, sizeof(data), NETCONN_NOCOPY);

netconn_close(conn);

netconn_delete(conn);
}
}

here i open a new connection and connect it to Server using its IPaddress


Before that I wanted to check the connection whether it is connected o
not, so what i did is i assigned a variable "err" and when I try to prin
it out on the terminal instrument and see the value it gives a value o
"-4".
Is this correct what I am doing here so that if i get a negative value tha
means the client is successfully connected to the server.
If so how can i transfer the data "Hello World" on to my server and get i
displayed there.
Kind Regards,
Greek

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