text: //
  // Created by adamzeng on 2019-06-10.
  //
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  #include <arpa/inet.h>
  #include <sys/socket.h>
  
  #define BUF_SIZE 1024
  
  void error_handling(char *message);
  
  int main(int argc, char **argv) {
      int sock;
      char message[BUF_SIZE];
      int str_len, recv_len, recv_cnt;
      struct sockaddr_in serv_adr;
  
      if (argc != 3) {
          printf("Usage: %s <IP> <port>\n", argv[0]);
          exit(1);
      }
  
      sock = socket(PF_INET, SOCK_STREAM, 0);
      if (sock == -1) {
          error_handling("socket() error");
      }
  
      memset(&serv_adr, 0, sizeof(serv_adr));
      serv_adr.sin_family = AF_INET;
      serv_adr.sin_addr.s_addr = inet_addr(argv[1]);
      serv_adr.sin_port = htons(atoi(argv[2]));
  
      if (connect(sock, (struct sockaddr *) &serv_adr, sizeof(serv_adr)) == -1) {
          error_handling("connect() error!");
      } else {
          puts("Connected............");
      }
  
      while (1) {
          fputs("Input message(Q to quit): ", stdout);
          fgets(message, BUF_SIZE, stdin);
  
          if (!strcmp(message, "q\n") || !strcmp(message, "Q\n")) {
              break;
          }
  
          str_len = write(sock, message, strlen(message));
  
          recv_len = 0;
          while (recv_len < str_len) {
              recv_cnt = read(sock, &message[recv_len], BUF_SIZE - 1);
              if (recv_cnt == -1) {
                  error_handling("read() error!");
              }
              recv_len += recv_cnt;
          }
  
          message[str_len] = 0;
          printf("Message from server: %s", message);
      }
  
      close(sock);
      return 0;
  }
  
  void error_handling(char *message) {
      fputs(message, stderr);
      fputc('\n', stderr);
      exit(1);
  }
  
  