Vs code error : when code splitting

Hi I’m new to vs code and I can’t figure out what’s wrong with this.
I’m spending a lot of time because of this problem.
Help me :frowning:

I made ( main.cpp / Car.cpp / Car.h )
I’ve included them just fine but I got an( Undefined symbols for architecture x86_64: ) error message and got ( clang: error: linker command failed with exit code 1 (use -v to see invocation) )

My code has nothing wrong because I completely copied the code from a book.
Also it worked fine before splitting my code into three files.
The worst part is I got upset and made a completely same code with Xcode, and it worked fine too!
I can’t understand this you have to help me.

here’s my code.

--------------Car.cpp---------------
#include
#include
#include “Car.h”

void Car::InitMembers(const char *ID, int fuel)
{
strcpy(gamerID, ID);
fuelGauge = fuel;
curSpeed = 0;
}

--------------Car.h---------------

#ifndef CAR_H
#define CAR_H

namespace CAR_CONST
{
enum
{
ID_LEN = 20,
};
}

class Car
{
private:
char gamerID[CAR_CONST::ID_LEN];
int fuelGauge;
int curSpeed;
public:
void InitMembers(const char *ID, int fuel);
};

#endif

--------------main.cpp---------------
#include “Car.h”
#include

int main()
{
Car run99;
run99.InitMembers(“run99”, 100);

return 0;

}

there are missing keywords while writing my codes.
include iostream
include string
they did not show up in my upper code