Xcode：clang：-1：链接器命令失败，退出代码为1（使用-v查看调用）

Question

我正在尝试编译该程序，但我在报告日志中不断收到此错误

Undefined symbols for architecture x86_64:
  "Net::feedForward(std::__1::vector<int, std::__1::allocator<int> > const&)", referenced from:
      _main in main.o
  "Net::backProp(std::__1::vector<int, std::__1::allocator<int> > const&)", referenced from:
      _main in main.o
  "Net::getResults(std::__1::vector<int, std::__1::allocator<int> >&) const", referenced from:
      _main in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

我的代码直接来自我尝试遵循的youtube教程，这是main.cpp代码：

#include <iostream>
#include <vector>
#include "Net.h"


int main() {
    vector<int> topology;
    Net myNet(topology);
    //constructor needs to know # of layers it wants & # neurons per layer

    vector<int> inputVals;
    vector<int> targetVals;
    vector<int> resultVals;
    myNet.feedForward(inputVals);
    //feeds inputs to begin with
    myNet.backProp(targetVals);
    //pass in some array with goal state
    myNet.getResults(resultVals);

}

Net.h代码：

#ifndef Net_hpp
#define Net_hpp

#include <stdio.h>
#include <vector>

using namespace std;

class Neuron{};
typedef vector<Neuron> Layer;

class Net{
public:
    Net(const vector<int> topology);
    void feedForward(const vector<int> &inputVals);
    void backProp(const vector<int> &targetVals);
    void getResults(vector<int> &resultVals) const;

private:
    vector<Layer> m_layers; //m_layers[layerNum][neuronNum]
};

#endif /* Net_hpp */

和Net.cpp代码：

#include "Net.h"
#include <vector>

Net::Net(const vector<int> topology){
    int numLayers = topology.size();
    for(int layerNum = 0; layerNum < numLayers; ++layerNum){


    }
}

我真的不知道如何解决它，而其他类似问题的线程也没有帮助。如果有人可以帮助我，我将不胜感激。