“体系结构x86_64的未定义符号”

Question

当我尝试编译代码时，我一直收到此错误，但我似乎不明白为什么。

Undefined symbols for architecture x86_64:
  "Location::Location()", referenced from:
      _main in main-64d6fd.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

我使用“ g ++ * main.cpp”来尝试对其进行编译，但是无论我做什么，都会遇到相同的错误。

#include <iostream>
#include "location-proj.h"
using namespace std;
int main() {

    Location loc;
    return 0;
}

#include <iostream>

using namespace std;

class Location {
public:
    Location();

private:
    int row, col;
    unsigned int nextDirection; //Uses ENUM as input
};

#include "location-proj.h"
Location::Location() {
    this->row = 0;
    this->col = 0;
    this->nextDirection = 0;
}