C++ 编译错误 : ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

Question

有人可以解释一下我在这里做错了什么吗？我正在使用 macOS 以下是代码:

//测试.h

#include <iostream>
#include <string>
class Test 
{
public:
    Test (std::string, std::string, int);

private:
    std::string par1;
    std::string par2;
    int par3;
};

//测试.cpp

#include <string>
#include <string>
#include "test.h"

using namespace std;

Test::Test (string first, string second, int third)
{
    par1 = first;
    par2 = second;
    par3 = third;
}

//mainTest.cpp

#include <string>
#include <iostream>
#include "test.h"

using namespace std;

int main()
{
    Test test1 ("A", "B", 2);
}

我用来编译的命令是:

g++ mainTest.cpp -o mainTest

这是我得到的错误:

Undefined symbols for architecture x86_64:
  "Test::Test(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, int)", referenced from:
      _main in mainTest-056a8f.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

我已经搜索了 stackoverflow 和谷歌，但我仍然无法弄清楚我做错了什么。非常感谢

Answer 1

您没有链接到 test.o。

g++ -c test.cpp -o test.o
g++ mainTest.cpp test.o -o mainTest

或者您可以同时进行这两项操作:

g++ maintest.cpp test.cpp -o mainTest