G++ undefined reference to class::function [duplicate]

Question

I'm finally pretty desperate. So, in my c++ class we were instructed to use classes. We'd have the header file declare the class and functions while a separate .cpp file implements the it. Things should be working, but they're not and no solutions on the web seem to be working for me. I'm using the G++ compiler on linux for this, and it doesn't seem to work on either IDE's or the normal command line.

The error I'm getting in my TBook.h is this:

/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o: In function `_start': (.text+0x20): undefined reference to `main' /tmp/ccxqI6An.o: In function `TBook::TBook()': TBook.cpp:(.text+0x3b): undefined reference to `Telephone::Telephone()' TBook.cpp:(.text+0x100): undefined reference to `Telephone::Telephone()' TBook.cpp:(.text+0x132): undefined reference to `Telephone::allNum(std::basic_string<char, std::char_traits<char>, std::allocator<char> >)' TBook.cpp:(.text+0x182): undefined reference to `Telephone::~Telephone()' TBook.cpp:(.text+0x191): undefined reference to `Telephone::~Telephone()' TBook.cpp:(.text+0x2b3): undefined reference to `Telephone::~Telephone()' TBook.cpp:(.text+0x2e6): undefined reference to `Telephone::~Telephone()' TBook.cpp:(.text+0x2fa): undefined reference to `Telephone::~Telephone()' /tmp/ccxqI6An.o:TBook.cpp:(.text+0x370): more undefined references to `Telephone::~Telephone()' follow /tmp/ccxqI6An.o: In function `TBook::write()': TBook.cpp:(.text+0x4e1): undefined reference to `Telephone::getNumber()' TBook.cpp:(.text+0x506): undefined reference to `Telephone::getAreaCode()' TBook.cpp:(.text+0x53a): undefined reference to `Telephone::getName()' /tmp/ccxqI6An.o: In function `TBook::lookup(std::basic_string<char, std::char_traits<char>, std::allocator<char> >)': TBook.cpp:(.text+0x6d4): undefined reference to `Telephone::getName()' TBook.cpp:(.text+0x79e): undefined reference to `Telephone::Telephone(int, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >)' /tmp/ccxqI6An.o: In function `TBook::print()': TBook.cpp:(.text+0x880): undefined reference to `Telephone::getName()' TBook.cpp:(.text+0x8e0): undefined reference to `Telephone::getNumber()' TBook.cpp:(.text+0x8ff): undefined reference to `Telephone::getAreaCode()' collect2: ld returned 1 exit status [Finished in 0.3s with exit code 1] 

I'm kind of not liking that the file is not receiving any of the Telephone class's methods. Here's what the code looks like for TBook.h:

#ifndef TBOOK_H #define TBOOK_H  #include "Telephone.h"  class TBook{ private:     Telephone rolodex[10];      int current;     int max; public:     TBook();     ~TBook();     void add(Telephone);     void write();     bool is_full();     void print();     void check();     Telephone lookup(string);  };  #endif 

And this is what TBook.cpp looks like:

#include <iostream> #include <fstream> #include <string>  #include "TBook.h" #include "Telephone.h"   using namespace std;  TBook::TBook(){     current = 0;     max = 9;      cout << "Hello" << endl;      string line;     ifstream myfile ("rolodex.txt");     if (myfile.is_open()){         while ( getline (myfile,line) ){             cout << line << endl;             Telephone t;             t.allNum(line);             add(t);          }         myfile.close();     }else if (!myfile.is_open()){         ofstream myfile;         myfile.open ("rolodex.txt");         myfile << "This is an empty file (Relatively).";         myfile.close();     } }  TBook::~TBook(){  }  void TBook::add(Telephone tel){     if (!is_full()){         rolodex[current] = tel;         current++;     } }  void TBook::write(){     ofstream myfile;     myfile.open ("rolodex.txt");     for (int i = 0; i < current; ++i)     {         myfile << rolodex[i].getName() << "," << rolodex[i].getAreaCode() << "," << rolodex[i].getNumber() << "\n";     }     myfile.close(); }  bool TBook::is_full(){     if (current <= max){         return false;     }     return true; }  Telephone TBook::lookup(string lookName){     for (int i = 0; i < current; ++i){         if (rolodex[i].getName() == lookName){             return rolodex[i];         }     }     return Telephone(100, "", "1000000"); }  void TBook::print(){     //Print the vairables     for (int i = 0; i < current; ++i){         cout << "Name: " << rolodex[i].getName() << endl;     cout << "Number: (" <<  rolodex[i].getAreaCode() << ") " << rolodex[i].getNumber() << endl;     }  }  void TBook::check(){     cout << "the message" << endl; } 

Since the problem seems to be arising with the Telephone class, I figure I should also show that code too

Telephone.h

..

#ifndef TELEPHONE_H #define TELEPHONE_H  #include <iostream> #include <string>   using std::string;  class Telephone{ private:     string name;     string num;     int areaCode; public:     Telephone(int, string, string);     Telephone();     ~Telephone();     bool setAreaCode(int);      //Setters      void setName(string);     void setNumber(string);     bool allNum(string);      //Getters     string getName();     string getNumber();     int getAreaCode();      //Checks     bool checkX(int);     bool checkY(int);   };  #endif 

Telephone.cpp

..

#include <iostream> #include <string> #include <stdio.h> #include <stdlib.h>  #include "Telephone.h"  using namespace std;  Telephone::Telephone(){     areaCode = 0     name = "";     num = ""; }  Telephone::Telephone(int aCode, string nam, string number){    areaCode = aCode;    name = name;  }  Telephone::~Telephone(){     //Nope Nada }  bool Telephone::allNum(string all){     size_t found =  all.find_first_of(",");      //     string first = all.substr(0, found);     string second = all.substr((found)+1, found+1);     string third = all.substr( all.find_last_of(",")+1, all.length());     int x, y;     //convert string to int values     if(third.length() == 7){         x = atoi(third.substr(0,3).c_str()),          y = atoi(third.substr(3,4).c_str());     }else{         cerr << "Your phone number is not valid" << endl;     }        int ac = atoi(second.substr(0, second.length()).c_str());      setName(first);     if (!setAreaCode(ac)){           setAreaCode(100);         return true;      }     if (!checkX(x) || !checkY(y)){             setNumber("1000000");         }else{             setNumber(third);     }      cerr << "The info provided is not valid" << endl;     return false; }  void Telephone::setNumber(string number){     num = number; }  bool Telephone::setAreaCode(int aCode){     if(aCode >= 100 && aCode <= 999){         areaCode = aCode;         return true;     }     return false; }  void  Telephone::setName(string theName){     name = theName; }  bool Telephone::checkX(int x){     if(x >= 100 && x <= 999){         return true;     }     cerr << "First three digits are not valid" << endl;     return false; }  bool Telephone::checkY(int y){     if(y >= 0000 && y <= 9999){         return true;     }     cerr << "Last four digits are not valid" << endl;     return false; }    //Getters string Telephone::getName(){     return name; }  string Telephone::getNumber(){     return num; }  int Telephone::getAreaCode(){     return areaCode; } 

And my main file (also called test.cpp) looks like this:

test.cpp

#include <iostream> #include <string> #include "TBook.h" #include "Telephone.h"  using namespace std;   int main(int argc, char const *argv[]) {     //Create a Rolodex     TBook addressBook;      return 0; } 

I'm also getting this error with test.cpp

/tmp/ccl8anRb.o: In function `main': test.cpp:(.text+0x24): undefined reference to `TBook::TBook()' test.cpp:(.text+0x38): undefined reference to `TBook::~TBook()' collect2: ld returned 1 exit status 

I think this is mostly a compiling error, but I'm still not sure, and I feel like I'm the setup of the meme "My code doesn't work, and I don't know why." Usually I would bash the code and try different methods until it works, but I simply don't have the time. I therefore need your help.

Answer 1

This is a linker error. Try:

g++ test.cpp Telephone.cpp -o test 

Basically, the linker is complaining about functions you used but didn't provide an implementation for. To see all the steps the compiler performs for you, throw in a -v:

g++ -v test.cpp Telephone.cpp -o test