dialog box problem keeps haunting me

Bleech · 08-23-2006, 12:41 AM

hey all,
I am just experimenting as I seem to be having very bad luck with creating dialog boxes with the API.

well, I FINALLY got some code to work that actually displays the dialog box (usually the code will compile fine, but when I execute it there is no sign of the dialog box).

here it is:

Code:

#include <windows.h>
#include "resource.h"

BOOL CALLBACK DialogProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	switch(uMsg) {
	case WM_INITDIALOG:
		SetDlgItemText(hwndDlg, IDC_EDIT, "hello there");
		return TRUE;
	case WM_CLOSE:
		EndDialog(hwndDlg, 0);
		return TRUE;
	}
	return FALSE;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
	return DialogBox(hInstance, MAKEINTRESOURCE(IDD_DIALOG), NULL, (DLGPROC)DialogProc);
}

yes, indeed very simple code. IDC_EDIT is an edit box control on the dialog (obviously). as I said, I figured I'd go real simple with this one since I was having so many troubles with other controls. I was so happy to see that the dialog actually appeared for once.

now here goes my question. on the dialog, there is also an OK (IDOK) button and a Cancel (IDCANCEL) button (by default). now, watch how I handle these button messages:

Code:

BOOL CALLBACK DialogProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	switch(uMsg) {
	case WM_INITDIALOG:
		SetDlgItemText(hwndDlg, IDC_EDIT, "hello there");
		return TRUE;
	case WM_COMMAND:
		switch(LOWORD(wParam)) {
		case IDOK:
			EndDialog(hwndDlg, 0);
			return TRUE;
		case IDCANCEL:
			EndDialog(hwndDlg, 0);
			return TRUE;
		}
	case WM_CLOSE:
		EndDialog(hwndDlg, 0);
		return TRUE;
	}
	return FALSE;
}

looks ok, right? thats what I thought. turns out that when I run this after this very small modification I get another one of those non appearing dialog boxes. lol

could anyone here please tell me what looks wrong with the way I am handling those button messages? I would really like to know what I am doing wrong to keep getting these non appearing dialog boxes (like what can cause behaviour like this? I am sure I'm not the only one here that has had this problem). the program appears to be completing execution, so maybe I am adding a return statement somewhere where I shouldn't be?

any help would be greatly appreciated, this same problem has been bugging me for a while now.

thanks in advance!

Cat · 08-23-2006, 12:55 AM

What would happen in your code if a WM_COMMAND message came that was neither IDOK nor IDCANCEL?

There's no default condition in your switch(LOWORD(wParam)) statement, nor is there a return or break after that switch, so any WM_COMMAND apart from IDOK or IDCANCEL will reach the end of that inner switch statement and then keep executing the contents of case WM_CLOSE.

Bleech · 08-23-2006, 01:12 AM

aha. my problem is not writing a break after WM_COMMAND (execution was falling through to WM_CLOSE). I was not expecting any messages to come other than the ones made by my controls. thanks for pointing that out Cat, here is my dialog callback now:

Code:

BOOL CALLBACK DialogProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	switch(uMsg) {
	case WM_INITDIALOG:
		SetDlgItemText(hwndDlg, IDC_EDIT, "hello there");
		return TRUE;
	case WM_COMMAND:
		switch(LOWORD(wParam)) {
		case IDOK:
			EndDialog(hwndDlg, 0);
			return TRUE;
		case IDCANCEL:
			EndDialog(hwndDlg, 0);
			return TRUE;
		default:
			return DefWindowProc(hwndDlg, uMsg, wParam, lParam);
		}
		break;
	case WM_CLOSE:
		EndDialog(hwndDlg, 0);
		return TRUE;
	}
	return FALSE;
}

08-23-2006, 12:41 AM	#1
Bleech Madly in anger with you Join Date: Nov 2005 Posts: 211	dialog box problem keeps haunting me hey all, I am just experimenting as I seem to be having very bad luck with creating dialog boxes with the API. well, I FINALLY got some code to work that actually displays the dialog box (usually the code will compile fine, but when I execute it there is no sign of the dialog box). here it is: Code: #include <windows.h> #include "resource.h" BOOL CALLBACK DialogProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam) { switch(uMsg) { case WM_INITDIALOG: SetDlgItemText(hwndDlg, IDC_EDIT, "hello there"); return TRUE; case WM_CLOSE: EndDialog(hwndDlg, 0); return TRUE; } return FALSE; } int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd) { return DialogBox(hInstance, MAKEINTRESOURCE(IDD_DIALOG), NULL, (DLGPROC)DialogProc); } yes, indeed very simple code. IDC_EDIT is an edit box control on the dialog (obviously). as I said, I figured I'd go real simple with this one since I was having so many troubles with other controls. I was so happy to see that the dialog actually appeared for once. now here goes my question. on the dialog, there is also an OK (IDOK) button and a Cancel (IDCANCEL) button (by default). now, watch how I handle these button messages: Code: BOOL CALLBACK DialogProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam) { switch(uMsg) { case WM_INITDIALOG: SetDlgItemText(hwndDlg, IDC_EDIT, "hello there"); return TRUE; case WM_COMMAND: switch(LOWORD(wParam)) { case IDOK: EndDialog(hwndDlg, 0); return TRUE; case IDCANCEL: EndDialog(hwndDlg, 0); return TRUE; } case WM_CLOSE: EndDialog(hwndDlg, 0); return TRUE; } return FALSE; } looks ok, right? thats what I thought. turns out that when I run this after this very small modification I get another one of those non appearing dialog boxes. lol could anyone here please tell me what looks wrong with the way I am handling those button messages? I would really like to know what I am doing wrong to keep getting these non appearing dialog boxes (like what can cause behaviour like this? I am sure I'm not the only one here that has had this problem). the program appears to be completing execution, so maybe I am adding a return statement somewhere where I shouldn't be? any help would be greatly appreciated, this same problem has been bugging me for a while now. thanks in advance! __________________ Intel Core 2 Quad Q6600 @ 2.40 GHz 3072 MB PC2-5300 DDR2 2 x 320 GB SATA (640 GB) NVIDIA GeForce 8400GS 256 MB PCI-E
Bleech is offline

08-23-2006, 12:55 AM	#2
Cat Registered User Join Date: May 2003 Posts: 1,199	What would happen in your code if a WM_COMMAND message came that was neither IDOK nor IDCANCEL? There's no default condition in your switch(LOWORD(wParam)) statement, nor is there a return or break after that switch, so any WM_COMMAND apart from IDOK or IDCANCEL will reach the end of that inner switch statement and then keep executing the contents of case WM_CLOSE. __________________ You ever try a pink golf ball, Wally? Why, the wind shear on a pink ball alone can take the head clean off a 90 pound midget at 300 yards.
Cat is offline

08-23-2006, 01:12 AM	#3
Bleech Madly in anger with you Join Date: Nov 2005 Posts: 211	aha. my problem is not writing a break after WM_COMMAND (execution was falling through to WM_CLOSE). I was not expecting any messages to come other than the ones made by my controls. thanks for pointing that out Cat, here is my dialog callback now: Code: BOOL CALLBACK DialogProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam) { switch(uMsg) { case WM_INITDIALOG: SetDlgItemText(hwndDlg, IDC_EDIT, "hello there"); return TRUE; case WM_COMMAND: switch(LOWORD(wParam)) { case IDOK: EndDialog(hwndDlg, 0); return TRUE; case IDCANCEL: EndDialog(hwndDlg, 0); return TRUE; default: return DefWindowProc(hwndDlg, uMsg, wParam, lParam); } break; case WM_CLOSE: EndDialog(hwndDlg, 0); return TRUE; } return FALSE; } __________________ Intel Core 2 Quad Q6600 @ 2.40 GHz 3072 MB PC2-5300 DDR2 2 x 320 GB SATA (640 GB) NVIDIA GeForce 8400GS 256 MB PCI-E
Bleech is offline

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