Member Avatar for LevyDee

So I finally decided to take on some Windows Programming, and everything is going fine, except this:

Edit: using this tutorial http://bobobobo.wordpress.com/2008/01/31/how-to-create-a-basic-window-in-c/

#include <windows.h>

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
	WNDCLASS myWindow;

	myWindow.cbClsExtra = 0;
	myWindow.cbWndExtra = 0;
	myWindow.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	myWindow.hCursor = LoadCursor(NULL, IDC_ARROW);
	myWindow.hIcon = NULL;
	myWindow.hInstance = hInstance;
	myWindow.lpfnWndProc = WndProc;
	myWindow.lpszClassName = TEXT("Levi");
	myWindow.lpszMenuName = 0;
	myWindow.style = CS_VREDRAW | CS_HREDRAW;

	RegisterClass(&myWindow);

	HWND myHandle = CreateWindow(TEXT("Levi"), TEXT("My Window"), WS_OVERLAPPEDWINDOW, 10, 10, 200, 200, NULL, NULL, hInstance, NULL);


	

}

error C2065: 'WndProc' : undeclared identifier

Every tutorial Ive found uses WndProc but its telling me other wise.

Any Ideas? Thanks

Edited by LevyDee because: n/a
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  • Latest Post Latest Post by nithy.sweety

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Generated

The compiler error means the window procedure name you put into myWindow.lpfnWndProc doesn't exist where the compiler can see it. As noted, you need a WndProc; was close but the posted prototype had typos and a different name. Fixes: either implement WndProc before WinMain, or put a correct forward declaration above WinMain.

A minimal correct WndProc (use this exact name if you assign lpfnWndProc = WndProc) looks like:

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch (msg) {
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hwnd, msg, wParam, lParam);
}

You also need the standard message loop and to show/update the window after CreateWindow(...). Typical code to put inside WinMain after CreateWindow:

MSG msg;
ShowWindow(myHandle, nShowCmd);
UpdateWindow(myHandle);
while (GetMessage(&msg, NULL, 0, 0)) {
    TranslateMessage(&msg);
    DispatchMessage(&msg);
}
return (int)msg.wParam;

Troubleshooting notes: the function name must match exactly (case-sensitive in C++). CALLBACK matters because it sets the calling convention; mismatching signature will either give compile/link errors or runtime trouble. If you prefer, use WNDCLASSEX + RegisterClassEx (remember to set cbSize) and, on modern MSVC projects, be aware of UNICODE settings — that affects string literals and WinMain vs wWinMain.

Member Avatar for SCoder1

So I finally decided to take on some Windows Programming, and everything is going fine, except this:

Edit: using this tutorial http://bobobobo.wordpress.com/2008/01/31/how-to-create-a-basic-window-in-c/

#include <windows.h>

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
	WNDCLASS myWindow;

	myWindow.cbClsExtra = 0;
	myWindow.cbWndExtra = 0;
	myWindow.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	myWindow.hCursor = LoadCursor(NULL, IDC_ARROW);
	myWindow.hIcon = NULL;
	myWindow.hInstance = hInstance;
	myWindow.lpfnWndProc = WndProc;
	myWindow.lpszClassName = TEXT("Levi");
	myWindow.lpszMenuName = 0;
	myWindow.style = CS_VREDRAW | CS_HREDRAW;

	RegisterClass(&myWindow);

	HWND myHandle = CreateWindow(TEXT("Levi"), TEXT("My Window"), WS_OVERLAPPEDWINDOW, 10, 10, 200, 200, NULL, NULL, hInstance, NULL);


	

}

error C2065: 'WndProc' : undeclared identifier

Every tutorial Ive found uses WndProc but its telling me other wise.

Any Ideas? Thanks

You forgot the window procedure event handler

This may help....
cprogramming.com (Helps with c++ too)

Member Avatar for nithy.sweety

declare WinProc function...
LRESULT CALLBACK WinProc(HWND hwnd.UINT msg,WPARAM wparam,LPARAM lparam);

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