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Yet another undefined reference to class::function error

operandi (2)
I am new to C++ and objected-oriented programming, so please bear with me for this question. I am writing a date program that determines whether the date you input is a leap year, calculates length between two dates, among other things. Here's my code. It has a header file Date.h, and two source files Date.cpp and main.cpp:

Date.h
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    #include <iostream>
    using namespace std;
    class Date {
    private:
    static const int month_nb;
    static const unsigned char month_days[];
    static const unsigned char month_daysLeap[];
    protected:
    static bool testLeap(const int year_);
    bool isLeap;
    int year;
    int month;
    int day;
    public:
   

    Date(const int month_,const int day_,const int year_);
   

    ~Date(){};
   
    
    int get_month() const {return month;}
    int get_day() const {return day;}
    int get_year() const {return year;}
    

    void set_month(int m){month = m;}
    void set_day(int d){day = d;}
    void set_year(int y){year = y;}
   

    bool testLeap() const;
    void out() const;
    bool testValid() const;
    int operator-(const Date & date) const;
    static int Julian(const Date & date1,const Date & date2);
    static double CountACT_365(const Date & date1,const Date & date2);
    static int Count30_360L(const Date & date1,const Date & date2);
    static double Count30_360(const Date & date1,const Date & date2);
    double CountACT_365(const Date & date) const;
    int Count30_360L(const Date & date) const;
    double Count30_360(const Date & date) const;
    };
    inline bool operator==(const Date& d1,const Date& d2)
    {
    return d1.get_month()==d2.get_month()
    && d1.get_day()==d2.get_day() && d1.get_year()==d2.get_year();
    }
    ostream& operator<<(ostream& os,const Date& d);


Date.cpp
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    #include <iostream>
    #include "Date.h"
    using namespace std;
    const int Date::month_nb = 12;
    const unsigned char Date::month_days[] = {31,28,31,30,31,30,31,31,30,31,30,31};
    const unsigned char Date::month_daysLeap[] = {31,29,31,30,31,30,31,31,30,31,30,31};
    Date::Date(const int month_, const int day_, const int year_)
    {
    year = year_; month = month_; day = day_;
    isLeap = testLeap();
    }
    bool Date::testLeap(const int year_)
    {
    //if the year is not a multiple of 4, this is not a leap year
    if(year_ % 4 != 0) return false;
    //if the year is a multiple of 100, this is not a leap year,
    //except if it is a multiple of 400.
    if(year_ % 100 == 0) {
    return year_ % 400 == 0;
    }
    return true;
    }
    bool Date::testLeap() const {
    return testLeap(year);
    }
    void Date::out() const
    {
    cout << (int)month <<"/"<< (int)day <<"/"<< year << endl;
    }
    bool Date::testValid() const {
    return (1 <= month && month <= month_nb && 1 <= day
    && ((isLeap && day <= month_daysLeap[month-1])
    || (!isLeap && day <= month_days[month-1])));
    }
    ostream& operator<<(ostream& os,const Date& d) {
    return os<<d.get_month()<<'/'<<d.get_day()<<'/'<<d.get_year();
    }

main.cpp
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     #include <iostream>
    #include "Date.h"
    using namespace std;
    int Count30_360L(Date date1, Date date2) {
    return 360 * (int) (date2.get_year() - date1.get_year())
    + 30 * (int) (date2.get_month() - date1.get_month())
    + (date2.get_day() - date1.get_day());
    }
    double Count30_360(Date date1, Date date2) {
    return (double) Count30_360L(date1, date2) / 360.0;
    }
    int main() {
    
    	Date SBday = Date(8,24,1971);
    	Date CBday = Date(9,28,1996);
    	cout <<"Time elapsed " << CBday - SBday<<endl;
    	cout << "Q: was 8/24/1971 in a leap year? A: "<<SBday.testLeap()<<endl;
    	cout <<"Count30_360L(SBday,CBday) = "<< Count30_360L(SBday,CBday)<<endl;
    	cout <<"Count30_360(SBday,CBday) = "<< Count30_360(SBday,CBday)<<endl;
    	cout <<"CountACT_365(SBday,CBday) = "<< Count30_360L(SBday,CBday)<<endl;
    	cout <<"CBday.Count30_360L(SBday) = "<< CBday.Count30_360L(SBday)<<endl;
    	cout <<"CBday.Count30_360(SBday) = "<< CBday.Count30_360(SBday)<<endl;
    	return 0;
    	}

I get the following error messages:

g++ -static-libgcc -static-libstdc++ -o HW1_2.exe main.o Date.o

main.o: In function `main':

...Debug/../main.cpp:24: undefined reference to `Date::operator-(Date const&) const' (line 16 above)

...Debug/../main.cpp:29: undefined reference to `Date::Count30_360L(Date const&) const' (line 21 above)

...Debug/../main.cpp:30: undefined reference to `Date::Count30_360(Date const&) const' (line 22 above)

Could anyone help me out? Thanks!
Last edited on
Disch (13742)
99 times out of 100, "Undefined Reference" means you declared a function, but never gave that function a body.

In this case, the - operator, Count30_360, and Count30_360L were declared (and called), but you never wrote bodies for them.
operandi (2)
ah, thanks for the reply! you're right.
Last edited on
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