/*
 * Demonstrate how C++ handles exceptions
 * This code is written mostly in C style, except that it uses C++'s support for exceptions
 * Exceptions can be thrown and caught, just like in Java
 * Different exception types are identified by their data type (e.g. int vs string)
 * This program prompts the user to enter a number on the command line and
 * throws different exceptions in response to different errors.
 * Author: Ying Li 
*/
#include <cstdio> //stdio.h in C
int main (int argc, char *argv[]) {
    for (;;) {
        int q;
        try {
            printf("Enter a number (0..9): ");
            int k = scanf("%d", &q); // read formatted from stdin
            if (k == 0) {
                scanf("%*s"); //read the value but ignore
                throw "value is not a number";
            }
            //this part is unnecessary, just show different types of exceptions
            if (q < 0) {
                    throw 3.0; }
            if (q < 0 || q > 9) {
                    throw q; }
        }
        catch (const char *s) {
            printf("Error: %s\n", s);
            continue;
        }
        catch (int v) {
            printf("Error: number %d is out of range (0..9)\n", v);
            continue; 
        }
        catch (...) {
            printf("Unspecified error\n");
            continue;
        }
        if (q == 0)
            break;
        }
    return 0; 
}