Undefined reference to object::function - c++

Question

i have been stuck on this for awhile now no matter how i compile it on cygwin i still can't get through it
Main.cpp
#include <iostream>
#include <istream>
#include <fstream>
#include <string>
#include <sstream>
#include <ctype.h>
#include <cstring>
#include <cstdlib>
#include "Message.h"
#include "Packet.h"
#include "main.h"
using namespace std;
void fillList(list<Message> messages, char *argv[]);
void printList(const list<Message> &messages);
int getMID(list<Message> &messages, stringstream &lines);
void create(list<Message> &messages, stringstream &lines);
bool exist(list<Message> &messages, stringstream &lines);
Message getMessage(int ID, list<Message> &messages);
void printList(const list<Message> &messages);
void fillList(list<Message> messages, char *argv[])
{
string lines;
ifstream files(argv[1]);
if(files.is_open())
{
int delimc = 0;
string line;
stringstream file;
while(getline(files,lines))
{
file << lines;
if(!exist(messages, file))
create(messages, file);
int ID = getMID(messages, file);
string fields[3];
while(getline(file, line, ':'), delimc != 3)
{
if(delimc != 0)
{
fields[delimc] = line;
}
delimc++;
}
getMessage(ID, messages).add(atoi(fields[1].c_str()), fields[2]);
delimc = 0;
}
files.close();
}
}
int getMID(list<Message> &messages, stringstream &lines)
{
std::string line;
getline(lines, line, ':'); //followed standard procedure for defining string (line)
return atoi(line.c_str());
}
void create(list<Message> &messages, stringstream &lines)
{
messages.push_back(getMessage(getMID(messages, lines), messages)); //getID takes 2 arguments
}
bool exist(list<Message> &messages, stringstream &lines)
{
list<Message>::iterator itr;
for(itr = messages.begin(); itr != messages.end(); itr++)
{
if(itr->Message::getID() == getMID(messages, lines)) //itr is not a pointer and if you want to point it use the correct way
return true;
}
return false;
}
Message getMessage(int ID, list<Message> &messages)
{
list<Message>::iterator itr;
for(itr = messages.begin(); itr != messages.end(); itr++)
{
if(itr->Message::getID() == ID) //itr is not a pointer and if you want to point it use the correct way
return *itr;
}
//return ; //no need to return null, even if you want to return still you have to assign memebers of messages as null seperately
}
void printList(list<Message> &messages)
{
list<Message>::iterator itr;
for(itr = messages.begin(); itr != messages.end(); itr++)
{
cout << itr->Message::toString(); //was stucked at it, you have to redesgn it in a way that you will first use add() and then packect.tostring() in order to print
}
cout << '\n';
}
int main(int argc, char *argv[])
{
cout << "The Program: " << argv[0] << " was created by Newbie";
list<Message> messages;
fillList(messages, argv);
printList(messages);
return 0;
}
//input argument for the text file
//read the file with limit of 2 splitter
//split it up and create the Message with packets
//display the msg
Message.cpp
#include <iostream>
#include <list>
#include <ctype.h>
#include <sstream>
#include "Packet.h"
using namespace std;
class Message
{
private:
int ID;
list<Packet> packets;
public:
Messages(int newID, list<Packet> newPackets)
{
ID = newID;
packets = newPackets;
}
int getID()
{
return ID;
}
void setID(const int &newID)
{
ID = newID;
}
list<Packet> getPackets()
{
return packets;
}
void add(int SQN, string text)
{
packets.push_back(Packet(SQN, text));
}
string toString()
{
ostringstream oss;
oss << "Message " << ID;
list<Packet>::iterator itr;
for(itr = packets.begin(); itr != packets.end(); itr++)
{
oss << itr->toString();
}
return oss.str();
}
};
Message.h
#ifndef Message_H
#define Message_H
#include <iostream>
#include <list>
#include <ctype.h>
#include <sstream>
#include "Packet.h"
using namespace std;
class Message
{
int ID;
list<Packet> packets;
public:
Message(int ID, list<Packet> packets);
int getID();
list<Packet> getPackets();
void setID(const int newID);
void setPackets(list<Packet> newPackets);
void add(int SQN, string text);
string toString();
};
#endif
i've tried to compile it but i keep getting the same error each time
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x1f3): undefined reference to `Message::add(int, std::string)'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x1f3): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Message::add(int, std::string)'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x4ed): undefined reference to `Message::getID()'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x4ed): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Message::getID()'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x592): undefined reference to `Message::getID()'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x592): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Message::getID()'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x63d): undefined reference to `Message::toString()'
/tmp/ccDZ0PKH.o:main.cpp:(.text+0x63d): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `Message::toString()'
compiling using cygwin
g++ main.cpp Message.cpp Packet.cpp

Answer 1

Your cpp file is wrong. You are defining a new class, Message, in the cpp file and defining its functions instead of giving definitions to the functions from the Message class in your header file. Your cpp file should look like this:
Message::Message(int newID, list<Packet> newPackets)
{
ID = newID;
packets = newPackets;
}
int Message::getID()
{
return ID;
}
void Message::setID(const int &newID)
{
ID = newID;
}
list<Packet> Message::getPackets()
{
return packets;
}
void Message::add(int SQN, string text)
{
packets.push_back(Packet(SQN, text));
}
string Message::toString()
{
ostringstream oss;
oss << "Message " << ID;
list<Packet>::iterator itr;
for(itr = packets.begin(); itr != packets.end(); itr++)
{
oss << itr->toString();
}
return oss.str();
}