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I am trying to understand header(.h) file and source file(.cpp) in c++. I wrote a very simple example to understand it. My operation system is Mac OS. I run "g++ main.cpp" in terminal. But it occur compile error as below:

Undefined symbols for architecture x86_64:
  "Date::Date(int, int, int)", referenced from:
      _main in main-0f869d.o
ld: symbol(s) not found for architecture x86_64

My code is as below. Please help, thanks

The main.cpp file: 

#include <iostream>
#include "Date.h"
using namespace std;

int main()
{
    Date d(2017, 08, 20);
    cout<<"getYear="<<d.getYear()<<endl;
    return 1;
}

The Date.h file:

#ifndef DATE_H
#define DATE_H

class Date
{
    private:
    int m_year;
    int m_month;
    int m_day;

    public:
        Date(int year, int month, int day);
        void SetDate(int year, int month, int day);

        int getYear() { return m_year; }
        int getMonth() { return m_month; }
        int getDay()  { return m_day; }
    };
#endif

The Date.cpp file:

#include "Date.h"

// Date constructor
Date::Date(int year, int month, int day)
{
    SetDate(year, month, day);
}

// Date member function
void Date::SetDate(int year, int month, int day)
{
    m_month = month;
    m_day = day;
    m_year = year;
}
Fantacsy
  • 11

1 Answers1

2

You need to include all the sources you'd like to compile.

g++ main.cpp Date.cpp -o binary_file

Josh
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