Question

HI

I’m writing a program that acts as a server and has the ability to interact with the user via the terminal. if i read from the stdin i want up to 140 chars.
if the user enters more than 140 i would like to take only the first 140 chars and ignore the rest.

i try something like the following code:

struct timeval timeout;
fd_set readings;
char buf[140];


while (1) {
    timeout.tv_sec = 15;
    timeout.tv_usec = 0;
    FD_ZERO(&readings);
    FD_SET(STDIN_FILENO,&readings);

    int rv = select(STDIN_FILENO+1,&readings,NULL,NULL,&timeout);
    if (rv<0) {
        cout << "ERROR select\n";
        exit(1);
    }
    if (rv==0) {
        cout << "Still Waiting...\n";
    }
    else {
        cout << "A key was pressed\n";
        if (FD_ISSET(STDIN_FILENO,&readings)) {
            int num = read(STDIN_FILENO,&buf,140);
            buf[num]='\0';
            cout << buf << endl;
        }
    }
}

the problem is – when i enter more than 140 chars, the first 140 chars are printed, but then read() reads the rest of the data in the next iteration and prints it .
how do i clear the stdin so that the rest of the data will be ignored in the next iteration?

thank you!!

Answer 1

Pretty much the only choice is to read the characters and discard them until end-of-line is reached.