c++ - 架构 x86_64 : Compiling problems 的 undefined symbol

Question

所以我正在尝试开始一项作业，我的教授给了我们一个 Main.cpp、Main.h、Scanner.cpp、Scanner.h 和一些其他实用程序。

我的工作是创建一个相似度类来使用余弦和 Jaccard 系数比较文档。但是，我似乎无法正确链接项目，因此无法从实际代码开始。

在尝试了几个小时来看看我做错了什么之后，我需要用新的眼光来看看我做错了什么，我怀疑这很明显。

这里是 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 Begin\n" << similarity.toString() << endl;
  outStream << TAG << "Data End\n" << 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;
}

还有 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

我的相似度.cpp

#include "Similarity.h"

using namespace std;

void readData(Scanner& inStream){
}

string maxCosine(){
    return "cosine";
}

string maxJaccard(){
    return "jaccard";
}

string toString(){
    return "toString";
}

最后是我的 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

当我使用他提供的 makefile 时，我必须使用这个文件才能让他的脚本对其进行评分，我收到此错误:

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

感谢您阅读所有内容，任何建议或解决方案将不胜感激。

Answer 1

这并不神秘，链接器告诉你你没有定义丢失的符号，而你没有。

Similarity::Similarity() 或 Similarity::~Similarity() 只是缺少，而您定义了其他错误，

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

不是

void readData(Scanner& inStream){
}

等等。等等

第二个是readData函数，只有第一个是Similarity类的readData方法。

要清楚这一点，在 Similarity.h 中

void readData(Scanner& inStream);

但在 Similarity.cpp 中

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