How do i fix this specific "undeclared identifier" error?

I am trying to learn how to make games and simulations in c using glad and glfw. This error occurred when trying to use the struct Window in any function as parameter or just to declare a Window instance. I am getting the 'Window': undeclared identifier error. I understood that this may mean that I have a circular include (which I can’t seem to figure out where) by researching the error on stackoverflow. (I am quite new to c, so any help I gladly appreciated)

Core.h:

#ifndef MINECRAFTCLONE_CORE_H
#define MINECRAFTCLONE_CORE_H

#include <stdio.h>

#include <glad/glad.h>
#include <GLFW/glfw3.h>

extern int error(char* error);

#endif

Core.c:

#include "Core.h"

int error(char* error)
{
    printf("%s", error);
    return -1;
}

Window.h:

#ifndef CORE_WINDOW_H
#define CORE_WINDOW_H

#include "Core.h"

struct Window
{
    int width;
    int height;
    char* title;
    GLFWwindow* res;
};

extern int coreCreateWindow(struct Window* window, int width, int height, char* title);
extern int coreLoopWindow(struct Window* window);

#endif

Window.c:

#include "Core.h"
#include "Window.h"

int coreCreateWindow(struct Window* window, int width, int height, char* title)
{
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 5);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    if (!glfwInit())
        return error((char*)"Failed to initialize glfw");

    window->width = width;
    window->height = height;
    window->title = title;
    window->res = glfwCreateWindow(window->width, window->height, window->title, 0, 0);

    if (!window->res)
        return error((char*)"Failed to create glfw window");

    glfwMakeContextCurrent(window->res);

    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
        return error((char*)"Failed to initialize glad");

    return 0;
}

int coreLoopWindow(struct Window* window)
{
    while (!glfwWindowShouldClose(window->res))
    {
        glfwPollEvents();
    }

    glfwDestroyWindow(window->res);
    glfwTerminate();

    return 0;
}

main.c:

#include "Core.h"
#include "Window.h"


int main()
{
    Window* window;

    return 0;
}

>Solution :

You have not defined a type called Window with which you could define a variable like

Window *window;

You have defined a struct Window with which you define your window variable in main() like

struct Window *window;

in the same way you are already defining all your function declaration’s window parameters.