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unresolved external symbol LNK2019

Ihop222 (5)
Hey, first time posting here, I read the "read here before posting" but apologies if I mess up.

I'm trying out inheritance for the first time and came across a set of LNK2019 errors which I haven't previously encountered. Tried searching but couldn't find anything that helped.

Errors:
Error LNK2019 unresolved external symbol "public: int __thiscall Date::getMonth(void)const " (?getMonth@Date@@QBEHXZ) referenced in function "public: int __thiscall Birthday::getAge(void)const " (?getAge@Birthday@@QBEHXZ

Error LNK2019 unresolved external symbol "public: __thiscall Date::Date(void)" (??0Date@@QAE@XZ) referenced in function "public: __thiscall Birthday::Birthday(int,int,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,int)" (??0Birthday@@QAE@HHV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@H@Z)

Error LNK2019 unresolved external symbol "public: int __thiscall Date::getDay(void)const " (?getDay@Date@@QBEHXZ) referenced in function "public: int __thiscall Birthday::getAge(void)const " (?getAge@Birthday@@QBEHXZ)


Code:

Date.h
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 #ifndef DATE_H_
#define DATE_H_
#include <string>
using namespace std;
class Date
{
public:
	Date();



	Date(int month, int day);
	
	Date(int month, int day, int year);

	
	int getMonth() const;

	
	int getDay() const;
	
	
	int getYear() const;
	
	void printDate1() const;

	void printDate2() const;

	int daysSinceJan1() const;

	long long daysSince() const;
	
	bool isLeapYear() const;

	string monthName() const;


	string dayName() const;

	bool equals(const Date& other) const;

	long long compareTo(const Date& other) const;

	void read();

	long long giveNumber();

protected:
	int month;
	int day;
	int year;
	int dayOfWeek;  //day of week in numerical format, 0 = sunday, 1= monday, ... , 6 = saturday
};

#endif DATE_H_

Birthday.h
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#include "Date.h"
#include <string>

class Birthday : public Date {
public:
	
	Birthday();
	/**
	* Constructor: birthday will always be this year
	* @param m month
	* @param d day
	* @param n name
	* @param y birth year
	*/
	Birthday(int month, int day, std::string name, int birthyear);
	/**
	* Calculates or gets the age of person with birthday
	* @return age of person with "this" birthday
	*/
	int getAge() const;
	/**
	* Gets the name of person with birthday
	* @return name of person with "this" birthday
	*/
	std::string getName() const;
	/**
	* Sets the name of person with birthday
	* @param n the name of person with "this" birthday
	*/
	void setName(std::string name);
	/**
	* Sets the year of birth of person with birthday
	* @param y the year the person with "this"
	* birthday was born
	*/
	void setBirthYear(int birthyear);
	/**
	* Extends printDate2 in base class and includes
	* " is so and so's birthday" at the end
	*/
	virtual void printDate2() const;
private:
	std::string name; // name of person with this birthday
	int birthYear; // birth year of the person

};

Birthday.cpp
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#include "Birthday.h"
#include "Date.h"
#include <string>
#include <ctime>
#include <cassert>
#include <iostream>

Birthday::Birthday() {
	time_t t = time(0); // get time now
	struct tm * now = localtime(&t);

	month = now->tm_mon + 1;
	day = now->tm_mday;
	birthYear = now->tm_year + 1900;
	dayOfWeek = now->tm_wday;
	name = "";

}

Birthday::Birthday(int monthIn, int dayIn, std::string nameIn, int birthyearIn) {
	month = monthIn;
	day = dayIn;
	name = nameIn;
	birthYear = birthyearIn;
}

int Birthday::getAge() const {
	int age = 0;  //january 1st 1990  january 2st 2008
	Date today;
	if (today.getMonth() == month) {
		if (today.getDay() >= day) {
			age = today.getYear() - birthYear;
		}
		else {
			age = today.getYear() - birthYear - 1;
		}
	}

	else if (today.getMonth() > month) {
		age = today.getYear() - birthYear;
	}
	else {
		age = today.getYear() - birthYear - 1;
	}
	return age;
}

std::string Birthday::getName() const {
	return name;
}

void Birthday::setName(string nameIn) {
	name = nameIn;
}

void Birthday::setBirthYear(int birthYearIn) {
	birthYear = birthYearIn;
}

void Birthday::printDate2() const {
	cout << monthName() << " " << day << ", " << birthYear << endl;
}


Can post the implementation of Date too if necessary, didn't want to add more than needed.
tpb (1495)
It says that Date::getMonth(), Date::getDay() and Date::Date() are not defined. Look in Date.cpp and see that they are all there.
Ihop222 (5)
Yeah they're all in Date.cpp. Also compiled and tested them separately and they worked fine.

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Date::Date()
{
	time_t t = time(0); // get time now
	struct tm * now = localtime(&t);

	month = now->tm_mon + 1;
	day = now->tm_mday;
	year = now->tm_year + 1900;
	dayOfWeek = now->tm_wday;
}

int Date::getMonth() const {
	return month;
}

int Date::getDay() const {
	return day;
}
tpb (1495)
Are those all the linker errors or does it also mention getYear, etc. ?
It seems strange that just three would be missing but the others would be there.

How are you compiling it?
Ihop222 (5)
Ah whoops, you're right missed three other errors.

Other three errors:

Error LNK2019 unresolved external symbol "public: int __thiscall Date::getYear(void)const " (?getYear@Date@@QBEHXZ) referenced in function "public: int __thiscall Birthday::getAge(void)const " (?getAge@Birthday@@QBEHXZ)

Error LNK2019 unresolved external symbol "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall Date::monthName(void)const " (?monthName@Date@@QBE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ) referenced in function "public: virtual void __thiscall Birthday::printDate2(void)const " (?printDate2@Birthday@@UBEXXZ)

Error LNK1120 5 unresolved externals

getYear, and monthName are also defined. I'm using visual studio, I just click Build Solution to compile.

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int Date::getYear() const {
	return year;
}

string Date::monthName() const {
	string monthName;
	if (month == 1) {
		monthName = "January";
	}
	else if (month == 2) {
		monthName = "February";
	}
	else if (month == 3) {
		monthName = "March";
	}
	else if (month == 4) {
		monthName = "April";
	}
	else if (month == 5) {
		monthName = "May";
	}
	else if (month == 6) {
		monthName = "June";
	}
	else if (month == 7) {
		monthName = "July";
	}
	else if (month == 8) {
		monthName = "August";
	}
	else if (month == 9) {
		monthName = "September";
	}
	else if (month == 10) {
		monthName = "October";
	}
	else if (month == 11) {
		monthName = "November";
	}
	else if (month == 12) {
		monthName = "December";
	}
	return monthName;
}
tpb (1495)
So you've created a project and all the cpp files and the header files are part of the project? In that case, it should work automatically and I don't know what's wrong.

You could maybe do without the switch:
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string Date::monthName() const {
	static const char *names[12] = {
		"January","February","March","April","May","June",
		"July","August","September","October","November","December"};
	return names[month];
}

Last edited on
Ihop222 (5)
That does look a lot neater, thanks. Yeah, I added them all into the project to start with, and rechecking now they all are listed to be a part of the project. Not sure what the problem is, think I'll try recreating the project and adding everything again.
Ihop222 (5)
Well not sure where I went wrong the first time, but everything appears to be compiling fine now after creating a new project and re-adding the files. Thanks for the help!
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