Checking the stdin buffer if it's empty

Question

I am trying to read a number character with character, but I don\'t know if the stdin buffer is empty or not.

My first solution whas to look for \'\\n\' character i

Answer 1

For anyone who comes here from google – easy select solution to check stdin emptyness:

fd_set readfds;
FD_ZERO(&readfds);
FD_SET(STDIN_FILENO, &readfds);
fd_set savefds = readfds;

struct timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = 0;

int chr;

int sel_rv = select(1, &readfds, NULL, NULL, &timeout);
if (sel_rv > 0) {
  puts("Input:");
  while ((chr = getchar()) != EOF) putchar(chr);
} else if (sel_rv == -1) {
  perror("select failed");
}

readfds = savefds;

Needs unistd.h, stdlib.h and stdio.h.

Explanation can be found here.

UPD: Thanks DrBeco for noticing that select returns -1 on error -- error handling was added.

Actually, select returns:

• the number of ready descriptors that are contained in the descriptor sets
• 0 if the time limit expires
• -1 if an error occurred (errno would be set)