chatappserver.c
#include<sys/socket.h>
#include<sys/types.h>
#include<stdio.h>
#include<arpa/inet.h>
#include<netinet/in.h>
#include<string.h>
#include<unistd.h>
#define SER_PORT 1200
int main()
{
int a,sersock,newsock,n;
char str[25],str2[25];
struct sockaddr_in seraddr;
struct sockaddr_in cliinfo;
socklen_t csize=sizeof(cliinfo);
seraddr.sin_family=AF_INET;
seraddr.sin_port=htons(SER_PORT);
seraddr.sin_addr.s_addr=htonl(INADDR_ANY);
if((sersock=socket(AF_INET,SOCK_STREAM,0))<0)
{
error("\n socket");
exit(0);
}
if(bind(sersock,(struct sockaddr *)&seraddr,sizeof(seraddr))<0)
{
error("\nBIND");
exit(0);
}
if(listen(sersock,1)<0)
{
error("\n LISTEN");
}
if((newsock=accept(sersock,(struct sockaddr *)&cliinfo,&csize))<0)
{
error("\n ACCEPT");
exit(0);
}
else
printf("\n now connected to %s\n",inet_ntoa(cliinfo.sin_addr));
read(newsock,str,sizeof(str));
do
{
printf("\n client msg:%s",str);
printf("\n server msg:");
scanf("%s",str2);
write(newsock,str2,sizeof(str2));
listen(newsock,1);
read(newsock,str,sizeof(str));
n=strcmp(str,"BYE");
a=strcmp(str2,"BYE");
}
while(n!=0||a!=0);
close(newsock);
close(sersock);
return 0;
}

chatappclient.c
#include<stdio.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<arpa/inet.h>
#include<netinet/in.h>
#include<unistd.h>
#define SER_PORT 1200
int main(int count,char*arg[])
{
int a,clisock;
char str[20],str2[20];
struct sockaddr_in cliaddr;
cliaddr.sin_port=htons(SER_PORT);
cliaddr.sin_family=AF_INET;
cliaddr.sin_addr.s_addr=inet_addr(arg[1]);
clisock=socket(AF_INET,SOCK_STREAM,0);
if(clisock<0)
{
perror("\n SOCKET");
exit(0);
}
if(connect(clisock,(struct sockaddr*)&cliaddr,sizeof(cliaddr))<0)
{
perror("\n CONNECT");
exit(0);
}
printf("\nclient connected to %s",arg[1]);
printf("\nCLIENT");
scanf("%s",&str);
if(write(clisock,str,sizeof(str))<0)
{
printf("\n data could not be sent");
}
do
{
listen(clisock,1);
read(clisock,str2,sizeof(str2));
printf("\nserver msg:%s",str2);
printf("\nclient msg:");
scanf("%s",&str);
a=strcmp(str2,"BYE");
write(clisock,str2,sizeof(str2));
}
while(a!=0);
close(clisock);
return 0;
}