c++ - UNIX-based chatroom::storing each character using getch(), POSIX threads -

all.

i having small issue unix-based chatroom utilizes p-thread library , bsd sockets.

at point, client able connect server, login desired username, , select room join. also, messages can sent server , received messages printed screen correctly. text based.

in client program, there main thread allows user press characters pushed onto vector; looks this:

    std::vector<char> current_message;/*global*/     while(1)     {       c = '\0';       while(c != '\n')/*break when enter pressed(send message)*/       {                 c = my_getch();          if((c == '\n' && current_message.size() == 0)/*cannot send blank messages*/              || (c == 127 && char_count == 0))          {             c = '\0';             continue;          }           if(!my_isarrow(c))          {             if(c != 127)                char_count++;             else char_count--;             printf("%c", c);             current_message.push_back(c);          }          if(current_message.size() == 250)/*send message if close buf size*/             c = '\n';        }       send_message(current_message, server);       current_message.clear();/*remove characters already-sent buffer*/    } 

there thread procedure retrieves messages server procedure needed because need allow client send messages,concurrently, while waiting messages server.

the procedure looks this:

void *get_messages(void *data) {    pthread_detach(pthread_self());/*detach thread*/    int *sock = (int *) data;/*the thread data passed in socket                              use retrieve messages server*/    while(1)    {       packet_t pkt;       read(*sock, &pkt, sizeof(packet_t));/*block until message received*/       for(int = 0; < strlen(pkt.user_name); i++)       {          if(pkt.user_name[i] == '\n')             pkt.user_name[i] = '\0';       }       pthread_mutex_lock(&lock);        chat_buffer.push_back(pkt);        for(int = 0; < 50; i++)          printf("\n");/*emulate clearing of terminal window*/        for(int = 0; < chat_buffer.size(); i++)/*chat_buffer global vector*/                                                  /*that contains received messages*/       {          for(int j = 0; j < strlen(chat_buffer[i].msg); j++)          {             if(chat_buffer[i].msg[j] == '\n')/*remove newlines(inefficient)*/                chat_buffer[i].msg[j] = '\0';          }           /*print out received messages client terminal*/          printf("%s: %s\n", chat_buffer[i].user_name, chat_buffer[i].msg);        }       printf("----------------------------------------------------\n");/*some formatting readability*/       for(int = 0; < current_message.size(); i++)          printf("%c", current_message[i]);    *******this problem area******* } 

the problem in program occurs when 1 client (me) has typed in letters , pushed onto buffer. and, @ same time received message server , screen "refreshed." can see happening in get_messages(void *) procedure. however, when screen refreshing occurs, don't want (me) client's already-typed-in letters disappear; in order fix added line of code prints out letters in current_message vector. however, letters not printed out (even when code here says should be) note: characters in buffer show after press key on keyboard.

the code getch() function looks this:

int my_getch()/*this didn't come brain*/ {     struct termios oldt, newt;     int ch;     tcgetattr(stdin_fileno, &oldt);     newt = oldt;     newt.c_lflag &= ~(icanon | echo);     tcsetattr(stdin_fileno, tcsanow, &newt);     ch = getchar();     tcsetattr(stdin_fileno, tcsanow, &oldt);     return ch; } 

also, my_isarrow function parses incoming characters see if arrow key. want ignore arrow keys because moves cursor , down(i dont want this.)

so, has experienced problem or can see problem here have dealt?

regards, william.

the problem there because stdout buffered stream.

you need put fflush(stdout) after loop;

an aside fputc(current_message[i], stdout) instead of printf("%c", current_message[i]) that's bit more efficient:

here delta need:

  printf("----------------------------------------------------\n");/*some formatting readability*/   for(int = 0; < current_message.size(); i++) {      fputc(current_message[i], stdout);       }   fflush(stdout); /* make sure stdout flushed, stdout buffered */