the exact use of listen system call in socket-programming?

Question

is it for No of connection can be accepted?
or is it for no of client can be in queue while SFD is busy..?

i have kept 0 as an argument in listen, still it is taking 10 connection..
but if i remove listen then it is showing an error..

Can anybody please help in this?

Thanks in advance

Answer 1

You bind a socket to a IP Address and Port and server should listen on this for accepting the client connection. And for this purpose listen is used -

Syntax

int listen(int sockfd, int backlog);

socket is first created with socket system call, a willingness to accept incoming connections and 
a queue limit for incoming connections are specified with listen(), and then the connections are 
accepted with accept. The listen() call applies only to sockets of type SOCK_STREAM or SOCK_SEQPACKET.

The backlog parameter defines the maximum length the queue of pending connections may 
grow to. If a connection request arrives with the queue full the client may receive an error with 
an indication of ECONNREFUSED or, if the underlying protocol supports retransmission.