Date of birth validation with exceptions

Assumption: valid year is 1900 to 2100. Separate exception classes are used for day, month and year; each is caught by its own handler.

#include <iostream>
using namespace std;

class DayError   { public: int value;  DayError(int v)   : value(v) {} };
class MonthError { public: int value;  MonthError(int v) : value(v) {} };
class YearError  { public: int value;  YearError(int v)  : value(v) {} };

int main() {
    int d, m, y;
    cout << "Enter date of birth (day month year): ";
    cin >> d >> m >> y;
    try {
        if (y < 1900 || y > 2100) throw YearError(y);
        if (m < 1 || m > 12)      throw MonthError(m);

        int days[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
        bool leap = (y % 4 == 0 && y % 100 != 0) || (y % 400 == 0);
        if (leap) days[1] = 29;
        if (d < 1 || d > days[m - 1]) throw DayError(d);

        cout << "Date of birth: " << d << "/" << m << "/" << y << endl;
    }
    catch (DayError e)   { cout << "Invalid day: "   << e.value << endl; }
    catch (MonthError e) { cout << "Invalid month: " << e.value << endl; }
    catch (YearError e)  { cout << "Invalid year: "  << e.value << endl; }
    return 0;
}

Sample runs

Enter date of birth (day month year): 15 8 2002
Date of birth: 15/8/2002

Enter date of birth (day month year): 31 4 2002
Invalid day: 31

Enter date of birth (day month year): 10 13 2002
Invalid month: 13