I get this error is Visual Studio C++ :: "error LNK2019: unresolved external symbol" -

this question has answer here:

• what undefined reference/unresolved external symbol error , how fix it? 27 answers

i see there no shortage of these on site, @ wits end figure out. simple program 3 file. when attempt compile program link error. 3 files show in solution explorer.

here output

1>------ build started: project: problem 2, configuration: debug win32 ------ 1>build started 5/13/2013 8:33:06 pm. 1>initializebuildstatus: 1>  touching "debug\problem 2.unsuccessfulbuild". 1>clcompile: 1>  main.cpp 1>  dayofyear.cpp 1>  generating code... 1>manifestresourcecompile: 1>  outputs up-to-date. 1>main.obj : error lnk2019: unresolved external symbol "public: void __thiscall dayofyear::print(void)" (?print@dayofyear@@qaexxz) referenced in function _main 1>c:\users\digivision\desktop\school\cs-150-01\w11ch11\problem 2\debug\problem 2.exe : fatal error lnk1120: 1 unresolved externals 1> 1>build failed. 1> 1>time elapsed 00:00:01.72 ========== build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== 

here 3 files

main.cpp

#include <iostream> #include "dayofyear.h"  using namespace std;  int main() {     int num;         {         cout << "enter number (-1 escape): ";         cin >> num;         if (num != -1)         {             dayofyear day(num);             day.print();         }         cout << endl;     } while (num !=-1);      cout << endl;     return 0; } 

dayofyear.cpp

#include "dayofyear.h" #include <iostream>  using namespace std;  int number;  dayofyear::dayofyear(int n) {     number = n; }  void print() {     const char * const month[12] = {"january","february","march","april","may","june",                         "july","august","september","october","november","december"};      if (number < 32) // jan         cout << month[0] << " " << number;     else if (number < 60) // feb         cout << month[1] << " " << 60 - number;     else if (number < 91) // mar         cout << month[2] << " " << 91 - number;     else if (number < 121) // apr         cout << month[3] << " " << 121 - number;     else if (number < 152) // may         cout << month[4] << " " << 152 - number;     else if (number < 182) // jun         cout << month[5] << " " << 182 - number;     else if (number < 213) // jul         cout << month[6] << " " << 213 - number;     else if (number < 244) // aug         cout << month[7] << " " << 244 - number;     else if (number < 274) // sep         cout << month[8] << " " << 274 - number;     else if (number < 305) // oct         cout << month[9] << " " << 305 - number;     else if (number < 335) // nov         cout << month[10] << " " << 335 - number;     else if (number < 366) // dec         cout << month[11] << " " << 366 - number; } 

dayofyear.h

#ifndef dayofyear_h #define dayofyear_h  class dayofyear { private:     int number; public:     dayofyear()     {         number = 0;     }     dayofyear(int);     void print(); };  #endif 

definition of void print() in dayofyear.cpp should use :: operator

void dayofyear::print() {   //function body goes here } 

otherwise, not interpreted member function of class dayofyear.