tcp-client.c

#include <ctype.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define SIZE sizeof(struct sockaddr_in)
#define MYPORT 7091
main()
{
   int sockfd;
   char c, rc;
   struct sockaddr_in server = {AF_INET, MYPORT};

   server.sin_addr.s_addr = inet_addr("127.0.0.1");

   if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1){
      perror("socket call failed");
      exit(1);
   }
   if(connect(sockfd, (struct sockaddr *)&server, SIZE) == -1){
      perror("connect call failed");
      exit(1);
   }
   for(rc='\n';;){
      if(rc == '\n')
         printf("Input a lowercase character\n");
      c = getchar();
      send(sockfd, &c, 1, 0);

      if(recv(sockfd, &rc, 1, 0) > 0)
         printf("%c", rc);
      else{
         printf("server has died\n");
         close(sockfd);
         exit(1);
      }
   }
}