GetWindowText() doesn't work - c++

Question

Initially I have to say that I know nothing about WinAPI. I'm learning from quite old tutorial, which seems to be a little bit outdated. I'm trying to make a dialog box where user would type in size of a next window. I've made it in Visual Studio using Resource Editor (or whatever it is called). I'm trying to retrieve data from Edit Controls, but GetWindowText doesn't work well.
So I made global LPTSTR named SizeX and SizeY (I know I could made them local and later pass them to a function that creates the second window, but I've got then problems with hInstance... nevermind).
BOOL CALLBACK SettingsProcedure(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch (msg)
{
case WM_INITDIALOG:
{
SetWindowTextA(GetDlgItem(hwnd, IDC_EDIT1), "20"); //I'm setting default input in case the user doesn't want to write anything
SetWindowTextA(GetDlgItem(hwnd, IDC_EDIT2), "20");
}
break;
case WM_COMMAND:
{
switch (LOWORD(wParam))
{
case IDC_BUTTON1:
{
GetWindowText(GetDlgItem(hwnd, IDC_EDIT1), sizeX, GetWindowTextLength(GetDlgItem(hwnd, IDC_EDIT1)) + 1);
if (sizeX == NULL)
break; //breaks every time
GetWindowText(GetDlgItem(hwnd, IDC_EDIT2), sizeY, 10);
EndDialog(hwnd, IDC_BUTTON1);
}
break;
}
}
break;
default: return FALSE;
}
return TRUE;
}
I'm sure I have a lot of basic mistakes in this code, so please don't blame me :P
I have no idea how to make it work. The fantastic tutorial I use tells nothing about Edit Controls, it even has an information that it might be too old. Unfortunately that is the only WinAPI tutorial I've found in my language, if you know any good one in English I'd be glad.

Answer 1

the thing that you should do is use directly GetDlgItemInt to retrieve sizeX and sizeY otherwise you should get text as a string then convert it into int:
case WM_COMMAND:
{
switch (LOWORD(wParam))
{
case IDC_BUTTON1:
{
BOOL bCheck = FALSE;
sizeX = GetDlgItemInt(hwnd, IDC_EDIT1, &bCheck, false);
sizeY = GetDlgItemInt(hwnd, IDC_EDIT2, &bCheck, false);
// or text then convert:
int textLengthX = SendDlgItemMessage(hwnd, IDC_EDIT1, WM_GETTEXTLENGTH, 0, 0);
int textLengthY = SendDlgItemMessage(hwnd, IDC_EDIT2, WM_GETTEXTLENGTH, 0, 0);
LPSTR lpTextX = (LPSTR)GlobalAlloc(GPTR, textLengthX + 1);
LPSTR lpTextY = (LPSTR)GlobalAlloc(GPTR, textLengthY + 1);
SendDlgItemMessage(hwnd, IDC_EDIT1, WM_GETTEXT, (WPARAM)textLengthX + 1, (LPARAM)lpTextX);
SendDlgItemMessage(hwnd, IDC_EDIT1, WM_GETTEXT, (WPARAM)textLengthY + 1, (LPARAM)lpTextY);
// now you have sizeX and sizeY as strings so convert them to int:
int sizeX = atoi(lpTextX);
int sizeY = atoi(lpTextY);
GlobalFree(lpTextX);
GlobalFree(lpTextY);
}
break;
}
break;
}