SDL 2 undefined reference to `Window::Window(std::__cxx11::basic_string, std::allocator >, int, int)'

Question

//To note I just started learning SDL2 from 30th April so please be considerate of my lack of knowledge

I made a header file called "window.h" as a class.

And when I recall that window class in the main.cpp open a window with the input that i have entered,

the following error occured

PS C:\Users\Admin\Desktop\SDLTuto> make
g++ -I src/include -L src/lib -o main main.cpp -lmingw32 -lSDL2main -lSDL2 
C:\Users\Admin\AppData\Local\Temp\ccymEbqx.o:main.cpp:(.text+0x48): undefined reference to `Window::Window(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, int, int)'
C:\Users\Admin\AppData\Local\Temp\ccymEbqx.o:main.cpp:(.text+0x81): undefined reference to `Window::~Window()'
collect2.exe: error: ld returned 1 exit status
make: *** [Makefile:2: all] Error 1

This is the header file

#pragma once
#include <string>
#include <SDL2/SDL.h>

class Window {
public:
    Window(std::string title, int WIDTH, int HEIGHT);
    ~Window();
    inline const bool isClosed() {return closed;}
private:
bool init();

private:
    std::string _title;
    int _WIDTH = 800;
    int _HEIGHT = 600;

    bool closed = false;

    SDL_Window *window = nullptr;//nullptr = 0
};

And this the code that creates the window

#include "window.h"
#include <iostream>
//constructor
Window::Window(const std::string title, int WIDTH, int HEIGHT):
_title(title), _WIDTH(WIDTH), _HEIGHT(HEIGHT)
{
    if(!init()){
        closed = true;
    }
}

Window::~Window(){
    SDL_DestroyWindow(window);
    SDL_Quit();
}

bool Window::init(){
    if(SDL_Init(SDL_INIT_EVERYTHING)){
        std::cerr << "Failed to initialize SDL.\n";
        return 0;
    }
    window = SDL_CreateWindow(_title.c_str(), SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, _WIDTH, _HEIGHT, SDL_WINDOW_RESIZABLE);

    if (window == nullptr){
        std::cerr << "Failed to create window!\n";
        return 0;
    }

    return true;
}

And this is the main.cpp that calls the opening window cpp file

#include "window.h"

int main(int argc, char *argv[]){

    Window window("SDL TEST", 800, 600);

    while(!window.isClosed()){
        
    }
    return 0;
}

I put the header file in the include folder which contains SDL2 libraries

I have tried making a new project and moving the codes to the new one

Makefile

all:
    g++ -I src/include -L src/lib -o main main.cpp -lmingw32 -lSDL2main -lSDL2