Linux Server, client

#include <stdio.h>//standard input and output header file#include <sys/socket.h>//function declarations and structure definitions related to sockets#include <netinet/inch.h>//some struct declarations, macro definitions#include <arpa/inet.h>//some function declarations#include <errno.h>//Viewing error codes/*these are the necessary header files, several of which are required for almost every network program, such as <sys/socket.h>,<netinet/in.h>, etc.*/intMainintargcChar*argv[]) {printf ("=======================================\n"); printf ("= My First server program =\n"); printf ("=======================================\n"); intsockfd,new_fd;structsockaddr_in server_addr;structsockaddr_in client_addr;intSin_size,portnumber;Charhello[]="Hello, the network! This is my first server.\n"; if(argc!=2) {fprintf (stderr,"usage:%s portnumber \a\n", argv[0]); Exit (1);//Program error ended }if((Portnumber=atoi (argv[1])) <0) {fprintf (stderr,"usage:%s portnumber \a\n", argv[0]); Exit (1); }   //atoi () converts a character type to an integral type//set up the socket descriptor (intnet protocol cluster, stream socket, using default protocol) if(Sockfd=socket (Af_inet,sock_stream,0))==-1) {fprintf (stderr,"Socket error:%s \a\n", Strerror (errno)); Exit (1); }//populate the server's socket address structure SOCKADDRBzero (&AMP;SERVER_ADDR,sizeof(structsockaddr_in)); Server_addr.sin_family=af_inet; server_addr.sin_addr.s_addr=htonl (Inaddr_any); Server_addr.sin_port=htons (portnumber);//start bundling sockfd descriptors if(Bind (SOCKFD, (structSOCKADDR *) (&AMP;SERVER_ADDR),sizeof(structSOCKADDR)) ==-1) {fprintf (stderr,"Bind error:%s \a\n", Strerror (errno)); Exit (1); } //Monitoring SOCKFD descriptorsif(Listen (SOCKFD,5)==-1){   //fprintf (stderr, "Listen error:%s \a\n", Strerror (errno));Exit1); }   while(1) {//block the server until the client program establishes a connectionSin_size=sizeof(structsockaddr_in); if(New_fd=accept (SOCKFD, (structsockaddr*) (&AMP;CLIENT_ADDR), &sin_size)) ==-1){     //fprintf (stderr, "Accept error:%s \a\n", Strerror (errno));Exit1); } fprintf (stderr,"Server get connection from%s: \ n", Inet_ntoa (CLIENT_ADDR.SIN_ADDR)); if(Write (New_fd,hello,strlen (hello)) ==-1){       //fprintf (stderr, "Write error:%s \a\n", Strerror (errno));Exit1); }     //end of communication, continue to loop executionClose (NEW_FD);/*when the server finishes processing the client request, close the connection socket*/ }//turn off the listener socket descriptorClose (SOCKFD); exit (0); }

#include <stdio.h>#include<sys/socket.h>#include<netinet/inch.h>#include<arpa/inet.h>#include<errno.h>#include<netdb.h>/*including structure hostent (host environment), several functions of obtaining host information*/intMainintargcChar*argv[]) {printf ("=======================================\n"); printf ("= My First client program! =\n"); printf ("=======================================\n"); intsockfd,new_fd;structsockaddr_in server_addr;structHostent *host;intNbytes,portnumber;Charbuffer[1024x768]; if(argc!=3) {fprintf (stderr,"usage:%s hostname portnumber \a\n", argv[0]); Exit (1); }//Get server address if((Host=gethostbyname (argv[1]))==NULL) {fprintf (stderr,"HostName erro!"); Exit (1); } if((Portnumber=atoi (argv[2])) <0) {fprintf (stderr,"usage:%s hostname portnumber \a\n", argv[0]); Exit (1); } //establishing a client SOCKFD descriptor if(Sockfd=socket (Af_inet,sock_stream,0))==-1) {fprintf (stderr,"Socket error:%s \a\n", Strerror (errno)); Exit (1); }//before calling the function connect, you need to specify the socket address of the server process//filling the SOCKADDR structureBzero (&AMP;SERVER_ADDR,sizeof(structsockaddr_in)); Server_addr.sin_family=af_inet; Server_addr.sin_port=htons (portnumber);//server_addr.sin_addr= * (struct in_addr *) host->h_addr);//initiating a connection request establish a connection with the remote server if(Connect (SOCKFD,structSOCKADDR *) (&AMP;SERVER_ADDR),sizeof(structSOCKADDR)) ==-1) {fprintf (stderr,"Bind error:%s \a\n", Strerror (errno)); Exit (1); } //perform read-write data operations to display data on standard output if(Nbytes=read (Sockfd,buffer,1024x768))==-1) {fprintf (stderr,"Read Error:%s \ n", Strerror (errno)); Exit (1); } Buffer[nbytes]='\\'; printf ("Received:%s \ n", buffer);//End Communication//Close ConnectionClose (SOCKFD); exit (0); }

Linux Server, client