UNIX for Dummies Questions & Answers

socket(...
connect(...

socket(...
bind(...
listen(....
while (1)
{
     fd=accept(...)
     if (fd!=-1)
     {
     }
}

#define MYPORT 1034
int main()
{
 struct sockaddr_in sin;
 struct sockaddr_in cin;
 int s = socket(PF_INET,SOCK_STREAM,0);
 sin.sin_family = AF_INET;
 sin.sin_port = htons(MYPORT);
 sin.sin_addr.s_addr = INADDR_ANY;
 memset(sin.sin_zero,'\0',sizeof(sin.sin_zero));
 int check=bind(s,(struct sockaddr *)&sin,sizeof(sin));
 check=listen(s,5);
 addrlen=sizeof(cin);
//My server waits when below line is encountered
 s_client = accept(s,(struct sockaddr *)&cin,&addrlen);
//once client runs and connect is executed accept returns 0
 printf("hi %s\n",inet_ntoa(cin.sin_addr));
 char *buf;
 //the below recv is non blocking, it doesn't wait for client to send.
 recv(s_client,buf,100,0);
}

int main(int argc,char *argv[])
{
 struct sockaddr_in sin;
 struct sockaddr_in cin;
 struct hostent *hp;
 hp=gethostbyname(argv[1]);
 cin.sin_family = AF_INET;
 cin.sin_addr = *((struct in_addr *)hp->h_addr);
 cin.sin_port = htons(MYPORT);
 memset(cin1.sin_zero,'\0',sizeof(cin.sin_zero));
 int s = socket(PF_INET,SOCK_STREAM,0);
 int check = connect(s,(struct sockaddr *)&cin,sizeof(cin));
 char buf[100] = "from client";
 int len = strlen(buf);
 int bytes_sent = send(s,buf,len,0);
 printf("%d",bytes_sent); // output is 11
}