Four common functions: 
1) socket () 
Header file: 
# Include <sys/types.h> 
# Include <sys/socket.h> 
Function prototype: 
Int socket (INT domain, int type, int Protocol) 

Domain: protocol type, generally af_inet 
Type: Socket Type 
Protocol: used to specify the number of the transport protocol used by the socket. It is usually 
 set to 0. 


2) BIND () 
Header file: 
# Include <sys/types.h> 
# Include <sys/socket.h> 

Function prototype: 
Int BIND (INT sockfd, struct sockaddr * my_addr, int addrlen) 

Sockfd: Socket Descriptor 
My_addr: A sockaddr pointer pointing to information including the local IP address and port 
 number. 
Addrlen: usually set to sizeof (struct sockaddr) 


3) connect () 
Header file: 
# Include <sys/types.h> 
# Include <sys/socket.h> 

Function prototype: 
Int connect (INT sockfd, struct sockaddr * serv_addr, int addrlen) 

Sockfd: Socket descriptor of the target server 
Serv_addr: pointer containing the IP address and port number of the target machine 
Addrlen: sizeof (struct sockaddr) 


4 listen () 
Header file: 
# Include <sys/socket.h> 

Function prototype: 
Int listen (INT sockfd, int backlog );

Sockfd: Socket descriptor returned by the socket () system call 
Backlog: specify the maximum number of requests in the Request queue. incoming 
 connection requests will wait for accept () in the queue. 


5 accept () 
Header file: 
# Include <sys/types.h> 
# Inlcude <sys/socket.h> 

Function prototype: 
Int accept (INT sockfd, void * ADDR, int addrlen) 

Sockfd: indicates the socket descriptor to be monitored. 
ADDR: Usually a pointer to the sockaddr_in variable, which is used to store the information 
 of the host requesting the Connection Service. 
Addrlen: sizeof (struct sockaddr_in) 


6 send () 
Header file: 
# Include <sys/socket.h> 

Function prototype: 
Int send (INT sockfd, const void * MSG, int Len, int flags );

Sockfd: Socket descriptor used to transmit data 
MSG: pointer to send data 
Flags: 0 


7 Recv () 
Header file: 
# Include <sys/types.h> 
# Include <sys/socket.h> 

Function prototype: 
Int Recv (INT sockfd, void * Buf, int Len, unsigned int flags) 

Sockfd: Socket descriptor for receiving data 
Buf: buffer for storing data 
Len: Buffer Length 
Flags: 0 


8 sendto () 
Header file: 
# Include <sys/types.h> 
# Include <sys/socket.h> 

Function prototype: 
Int sendto (INT sockfd, const void * MSG, int Len, unsigned int flags, const struct sockaddr *To, int tolen );


9 recvfrom () 
Header file: 
# Include <sys/types.h> 
# Include <sys/socket.h> 

Function prototype: 
Int recvfrom (INT sockfd, void * Buf, int Len, unsigned int flags, struct sockaddr * From, int fromlen) 


10 read () write () 
Int read (int fd, char * Buf, int Len) 
Int write (int fd, char * Buf, int Len) 


11 Shutdown () 
Close (sockfd) 
Int Shutdown (INT sockfd, int how) 

Result: Various Functions related to socket programming were studied. Those are 
 the part of Socket IO and Basic Functions of Socket Programming.