int error = 0;

    if ((month == 1 || month == 3 || month == 5 || month == 7 ||
        month == 8 || month == 10 || month == 12) && ( day>31 || day<1) )
    {
        error = 1;
    }
    else if ((month == 4 || month == 6 || month == 9 || month == 11) && (day>30 || day<1) )
    {
        error = 1;
    }
    else if ((month == 2) && (year % 4 == 0) && (day>29 || day<1))
    {
        error = 1;
    }
    else if ((month = 2) && (year % 4 != 0) && (day>28 || day<1) )
    {
        error = 1;
    }
    else if ((year < 999) || (year > 10000))
    {
        status = 1;
    }
    if ((month < 1) || (month > 12))
    {
        error = 1;
    }