while (1) { /*Loop*/
        if ((scanf("%d",&num)) != 1) { /* If the input is not valid, raise an error flag */
            return -1;
        } /* If the input is valid and in range, return it to the calling function */
        if (num >= n1 && num <= n2)
            return num;
        else /* If the input is valid but not in range, try again... */
            printf("The number must be between %d-%d. Try again: ",n1,n2);
    }