架构 x86_64 的未定义符号：linker 错误

Question

I'm trying to do a test of basic linking for cpp files, I've been searching all over and am having a lot of trouble trying to find a solution. I understand that I have to include the header in both cpp's, but I'm having trouble trying to run these two together.

//testMain.cpp

#include <iostream>
#include <stdio.h>
#include "func.h"

using namespace Temp;

int main()
{
    getInfo();
    return 0;
}

//func.h

#ifndef FUNC_H
#define FUNC_H

#include <iostream>
#include <stdio.h>


namespace Temp{
int getInfo();
}


#endif

//functions.cpp
#include "func.h"

using namespace std;

int Temp::getInfo()
{

    return 5 + 6;
}

//error that I'm getting using VS Code
cd "/Users/jcbwlsn/Downloads/Coding/CPP/Workspace/RPG Project/src/" && g++ testMain.cpp -o testMain && "/Users/jcbwlsn/Downloads/Coding/CPP/Workspace/RPG Project/src/"testMain
Undefined symbols for architecture x86_64:
  "Temp::getInfo()", referenced from:
      _main in testMain-1f71a1.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Answer 1

You're supposed to specify all translation unit files when linking a C++ program.

Your program consists of two source files, testMain.cpp and functions.cpp .

Hence the compile-and-link command should be something like:

g++ testMain.cpp functions.cpp -o testMain

Alternatively you can compile each source into separately and then link them into an executable:

g++ -c testMain.cpp -o testMain.o
g++ -c functions.cpp -o functions.o
g++ testMain.o functions.o -o testMain

Having some kind of a Makefile helps to automate this.