c++ - Class won't work with .hpp file included in main, but does with .cpp file include in main -

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

i'm having issue classes in ide tells me have undefined reference constructor if include .hpp file in main, not if include .cpp file in main instead. problem in class , across various sites, should .h or .hpp file included in main. here files:

student.hpp

#ifndef student_hpp #define student_hpp  class student { private:     std::string lastname;     double gpa;  public:     student();     student(std::string lastname, double gpa);      void setlastname(std::string lastname);     std::string getlastname();      void setgpa(double gpa);     double getgpa(); };  #endif //student_hpp 

student.cpp

#include <iostream> #include "student.hpp" using namespace std;   student::student() {     lastname = "unknown";     gpa = 0.0; } student::student(string lastname, double gpa) {     lastname = lastname;     gpa = gpa; }  void student::setlastname(string lastname) {     lastname = lastname; }  string student::getlastname() {     return lastname; }  void student::setgpa(double gpa) {      gpa = gpa; }  double student::getgpa() {     return gpa; } 

main.cpp

#include <iostream> #include "student.hpp"  using namespace std;   int main() {     student liz = student();     cout << liz.getlastname() << endl;        return 0; } 

thanks help.

edit: doesn't appear duplicate me, don't have ability @ point understand linked page. if somehow says same thing, it's in language me , still needed help.

you should compile student.cpp , main.cpp together. e.g in linux

g++ main.cpp student.cpp -o a.out 

you 1 output named "a.out" links of them together. run a.out.

for windows codeblocks:

code::blocks - how compile multiple file projects

https://www.youtube.com/watch?v=oxac8t-gpvy