[lwip-users] fundamentally flawed attempt at a TCP send

[sirnails]

Hello All,
I am trying to send a string over TCP and believe i am having fundamental understanding problems... 
The code i am trying to cobble together (based upon http://www.nongnu.org/lwip/) is:

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	struct tcp_pcb *pcb;
	
	static char indexdata[] = "DAVE";

	pcb = tcp_new();					/* Create a new TCP PCB. */
	tcp_bind(pcb, NULL, 44444);				/* Bind the PCB to TCP port 80. */
	tcp_connect(pcb,0xC0A821AF,55555,tcp_write(pcb, indexdata, sizeof(indexdata), 1));
	
	tcp_close(pcb);

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a few questions:
- what is a PCB (Protocol Control Block) and what is it for? is it just a unique reference number for the specific connection?

- the code compiles correctly but when run gives a SIGSEGV fault :

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Program received signal SIGSEGV, Segmentation fault.
0x02005d48 in tcp_connect (pcb=0x2013d90, ipaddr=0xc0a821af, port=55555, 
    connected=0xfffffffa) at ../lwip/src/core/tcp.c:425
425	    pcb->remote_ip = *ipaddr;

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Im sorry to be asking such a stupid question, I hope you can help!
Dave xx

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