/* Demonstration of input with checking */
#include <stdio.h>

main () {
    int num_input, i, j, k;
    printf("Enter three values: ");
    num_input = scanf("%d %d %d", &i, &j, &k);
    while (num_input < 3) {
        /* An error has occurred. */

        /* First throw away the rest of the input line; we use
           the simple function, getchar, for this.  getchar() reads
           one character from the input and returns it as its result,. */
        while (getchar() != '\n'  /* i.e. newline */ ) {
            /* keep looping until getchar gets the newline. */
        }

        /* Now print the message */
        printf("You only typed %d values correctly.\n", num_input);
        printf("Try again: ");

        /* Re-read */
        num_input = scanf("%d %d %d", &i, &j, &k);
    }
    /* Here the values must be correct. */
    printf("Your correct input was %d, %d, and %d\n", i, j, k);
}