I was coding a program to open a window but when I tried to run it I got error code LNK2019, this is my first time using MSVS and a lot of the results are out dated. I also don’t know much about computers just about programming so a lot are too complicated going over my head I need it explained like I’m 5.

the code:

#include <windows.h>

LRESULT CALLBACK windowproc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
//this handles windows and the messages they get and it uses callback so we can callback to it
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd){
    // gives class name for a wide character

    int heightscreen = GetSystemMetrics(SM_CYSCREEN);
    //height of screen
    int widthscreem = GetSystemMetrics(SM_CXSCREEN);
    //width of screen

    const wchar_t CLASS_NAME[] = L"Excitble Mediums";

    WNDCLASS window = { 0 };
    //this is where we define window wich is where we give it a tton of attribute that will help make the window

    window.lpfnWndProc = windowproc;
    window.lpszClassName = CLASS_NAME;
    window.hInstance = hInstance;
    //basicly a void of any other object

    RegisterClass(&window);
    //registars a class for the rest of the code, the & makes a pointer

    //create window
    HWND hwnd = CreateWindowEx(
        WS_EX_OVERLAPPEDWINDOW, //idk seemed like the bset option and it cant be null change if neccercery
        CLASS_NAME,
        L"Excited meidum", //L makes it work dk why, good to rember tho
        WS_SIZEBOX | WS_VISIBLE | WS_POPUP, //jst chose the bst one add or change iif nessery
        0, 0, //xy pos
        widthscreem,
        heightscreen,
        NULL,
        NULL,
        hInstance,
        NULL);
    //"game"loop starts
    MSG msg{ 0 };
    while (GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    //this will run when the window can get messages
}

the error messgae:

unresolved external symbol "__int64 __cdecl windowproc(struct HWND__ *,unsigned int,unsigned __int64,__int64)" (?windowproc@@YA_JPEAUHWND__@@I_K_J@Z) referenced in function WinMain    

I’m not sure if this enough information so just leave a comment if not I’ll edit the post.

I tried following lot a tuts on how to fix it but most were outdated