#ifndef PORT
#define PORT 30000
#endif
#define MAX_BACKLOG 5
#define MAX_CONNECTIONS 12
#define BUF_SIZE 128

for (int i = 0; i < MAX_CONNECTIONS; i++) {
    if (users[i].sock_fd != -1) {
        int num_written = write(users[i].sock_fd, buf, strlen(buf));
        if (num_written != strlen(buf)) {
            printf("Error");
            return -1;
        }
    }
}