Undefined Symbols for architecture x86_64: Compiling problems

So I am trying to start an assignment, my professor gives us a Main.cpp, Main.h, Scanner.cpp, Scanner.h, and some other utilities.

My job is to create a Similarity class to compare documents using the cosine and Jaccard coefficients. However, I can not seem to get the project linked correctly, therefore I am unable to start on the actual code.

After trying for several hours to see what I am doing wrong, I need fresh eyes to see what I am doing wrong, I suspect it is obvious.

Here is the Main.cpp

#include "Main.h"

using namespace std;

static const string TAG = "Main: ";

int main(int argc, char *argv[])
{
  string inStreamName;
  string logStreamName;
  string outStreamName;

  ofstream outStream;
  string timeCallOutput;
  Scanner inStream;

  Similarity similarity;

  ///////////////////////////////////////////////////////////////
  // Boilerplate for naming files and opening files
  Utils::CheckArgs(3, argc, argv, "infilename outfilename logfilename");
  outStreamName = static_cast<string>(argv[2]);
  logStreamName = static_cast<string>(argv[3]);

  Utils::FileOpen(outStream, outStreamName);
  Utils::LogFileOpen(logStreamName);

  timeCallOutput = Utils::timecall("beginning");
  Utils::logStream << timeCallOutput << endl;
  Utils::logStream << TAG << "Beginning execution" << endl;

  Utils::logStream << TAG << "outfile '" << outStreamName << "'" << endl;
  Utils::logStream << TAG << "logfile '" << logStreamName << "'" << endl;
  Utils::logStream.flush();

  ///////////////////////////////////////////////////////////////
  // What follows here is the real work of this code.
  //   read the entire input file and echo it back
  //   compute the two similarity coefficients

  inStreamName = static_cast<string>(argv[1]);
  inStream.openFile(inStreamName);
  Utils::logStream << TAG << "infile '" << inStreamName << "'" << endl;
  Utils::logStream.flush();

  similarity.readData(inStream);

  outStream << TAG << "Data Beginn" << similarity.toString() << endl;
  outStream << TAG << "Data Endn" << endl;
  outStream.flush();
  inStream.close();

  outStream << TAG << "Begin similarity computation" << endl;
  outStream << TAG << "Maximum Jaccard similarity:n" <<
                       similarity.maxJaccard() << endl;
  outStream << TAG << "Maximum cosine similarity:n" <<
                       similarity.maxCosine() << endl;
  outStream << TAG << "End similarity computation" << endl;
  outStream.flush();

  ///////////////////////////////////////////////////////////////
  // Boilerplate for terminating gracefully
  Utils::logStream << TAG << "Ending execution" << endl;
  timeCallOutput = Utils::timecall("ending");
  Utils::logStream << timeCallOutput << endl;
  Utils::logStream.flush();

  outStream.flush();
  Utils::FileClose(outStream);

  Utils::FileClose(Utils::logStream);

  return 0;
}

And the Main.h

#ifndef MAIN_H
#define MAIN_H

#include "../../Utilities/Utils.h"
#include "../../Utilities/Scanner.h"

#include "Similarity.h"

class Main
{
public:
  int main();
  virtual ~Main();

private:

};

#endif // MAIN_H

My Similarity.cpp

#include "Similarity.h"

using namespace std;

void readData(Scanner& inStream){
}

string maxCosine(){
    return "cosine";
}

string maxJaccard(){
    return "jaccard";
}

string toString(){
    return "toString";
}

And finally my Similarity.h:

#ifndef SIMILARITY_H
#define SIMILARITY_H

#include "../../Utilities/Scanner.h"

class Similarity
{
public:
    Similarity();
    virtual ~Similarity();

    void readData(Scanner& inStream);
    string maxCosine();
    string maxJaccard();
    string toString();
private:

};

#endif

When I use the makefile he provided, and the one I have to use in order for his script to work to grade it I get this error:

g++ -O3 -Wall -o Similarity.o -c Similarity.cpp
g++ -O3 -Wall -o Aprog Main.o Similarity.o Scanner.o ScanLine.o Utils.o 
Undefined symbols for architecture x86_64:
  "Similarity::maxJaccard()", referenced from:
      _main in Main.o
  "Similarity::readData(Scanner&)", referenced from:
      _main in Main.o
  "Similarity::toString()", referenced from:
      _main in Main.o
  "Similarity::maxCosine()", referenced from:
      _main in Main.o
  "Similarity::Similarity()", referenced from:
      _main in Main.o
  "Similarity::~Similarity()", referenced from:
      _main in Main.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status
make: *** [Aprog] Error 1

Thank you for reading through all that, any suggestions or solutions would be greatly appreciated.

1 Answer

There’s no mystery here, the linker is telling you that you haven’t defined the missing symbols, and you haven’t.

Similarity::Similarity() or Similarity::~Similarity() are just missing and you have defined the others incorrectly,

void Similarity::readData(Scanner& inStream){
}

not

void readData(Scanner& inStream){
}

etc. etc.

The second one is a function called readData, only the first is the readData method of the Similarity class.

To be clear about this, in Similarity.h

void readData(Scanner& inStream);

but in Similarity.cpp

void Similarity::readData(Scanner& inStream){
}

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