• Deen O'Connor (31/31) Oct 08 2020 I was coding my project, and at some point it required to get
• Dennis (9/11) Oct 08 2020 Dont take the address of the `wstring`, use `wndName.ptr` instead.
• Deen O'Connor (2/4) Oct 08 2020 It worked, thanks a lot!
• =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= (18/53) Oct 08 2020 I using like this:
• Bastiaan Veelo (7/9) Oct 08 2020 You are taking the address of a slice and pass it as if it were a
• =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= (3/18) Oct 08 2020 and may be you find interesting this construction:

Deen O'Connor <deen.oconnor yandex.ru> writes:

I was coding my project, and at some point it required to get 
widow rectangle. GetWindowRect function returned 
ERROR_INVALID_WINDOW_HANDLE (0x578) error. This is where i 
detected the error. I then checked what the return value of 
FindWindowW was, and it was 0. GetLastError showed that there was 
ERROR_NOT_ALL_ASSIGNED (0x514) error.

So, to re-create the error, i did the following:
1 - Opened an app that has a window. In my case this was x32dbg, 
i chose it because it has a short window name without any spaces.
2 - Wrote a small program to check if the error will happen again:
import std.stdio;
import std.conv;
import core.sys.windows.windows;

void main(string[] args) {
     wstring wndName = "x32dbg";
     HWND hWnd = FindWindowW(null, cast(wchar*)&wndName);
     if (hWnd is null) {
         writeln("Error 0x" ~ to!string(GetLastError(), 16) ~ " in 
FindWindowW()!");
     } else {
         writeln("x32dbg window: 0x" ~ to!string(cast(uint)hWnd, 
16));
     }
}
3 - Ran this code with rdmd

Output said that there was an error.
This also happened with every window i tried to find no matter 
what. FindWindowA also failed.

The only reason i'm writing this is because i can find the window 
with x32dbg and a very similar C++ code works fine.
So, am i doing something wrong, or is this a bug?

Dennis <dkorpel gmail.com> writes:

On Thursday, 8 October 2020 at 19:39:05 UTC, Deen O'Connor wrote:
     wstring wndName = "x32dbg";
     HWND hWnd = FindWindowW(null, cast(wchar*)&wndName);

Dont take the address of the `wstring`, use `wndName.ptr` instead.

wstring is internally a fat pointer that looks like this:

struct wstring {
     size_t length;
     immutable(wchar)* ptr;
}

When taking the address `&wndName`, you get a pointer to this 
struct on the stack, not the actual string literal.

Deen O'Connor <deen.oconnor yandex.ru> writes:

On Thursday, 8 October 2020 at 19:49:04 UTC, Dennis wrote:
 Dont take the address of the `wstring`, use `wndName.ptr` 
 instead.

It worked, thanks a lot!

=?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:

On Thursday, 8 October 2020 at 19:39:05 UTC, Deen O'Connor wrote:
 I was coding my project, and at some point it required to get 
 widow rectangle. GetWindowRect function returned 
 ERROR_INVALID_WINDOW_HANDLE (0x578) error. This is where i 
 detected the error. I then checked what the return value of 
 FindWindowW was, and it was 0. GetLastError showed that there 
 was ERROR_NOT_ALL_ASSIGNED (0x514) error.

 So, to re-create the error, i did the following:
 1 - Opened an app that has a window. In my case this was 
 x32dbg, i chose it because it has a short window name without 
 any spaces.
 2 - Wrote a small program to check if the error will happen 
 again:
 import std.stdio;
 import std.conv;
 import core.sys.windows.windows;

 void main(string[] args) {
     wstring wndName = "x32dbg";
     HWND hWnd = FindWindowW(null, cast(wchar*)&wndName);
     if (hWnd is null) {
         writeln("Error 0x" ~ to!string(GetLastError(), 16) ~ " 
 in FindWindowW()!");
     } else {
         writeln("x32dbg window: 0x" ~ to!string(cast(uint)hWnd, 
 16));
     }
 }
 3 - Ran this code with rdmd

 Output said that there was an error.
 This also happened with every window i tried to find no matter 
 what. FindWindowA also failed.

 The only reason i'm writing this is because i can find the 
 window with x32dbg and a very similar C++ code works fine.
 So, am i doing something wrong, or is this a bug?

I using like this:

                 HWND hwnd = FindWindow( "Window", "Panel" );

                 if ( hwnd )
                 {
                     PostMessage( hwnd, APP_MAIN_MENU, 0, 0 );
                 }

     wstring wndName = "x32dbg";
     HWND hWnd = FindWindowW(null, cast(wchar*)&wndName);

I think some like this...

LPCWSTR toLPCWSTR( string s ) nothrow // const wchar_t*
{
     import std.utf : toUTFz, toUTF16z, UTFException;
     try                        { return toUTF16z( s ); }
     catch ( UTFException e )   { return "ERR"w.ptr; }
     catch ( Exception e )      { return "ERR"w.ptr; }
}
alias toLPCWSTR toPCWSTR;

wstring wndName = "x32dbg";
HWND hWnd = FindWindowW( null, wndName.toLPCWSTR );

Bastiaan Veelo <Bastiaan Veelo.net> writes:

On Thursday, 8 October 2020 at 19:39:05 UTC, Deen O'Connor wrote:
     HWND hWnd = FindWindowW(null, cast(wchar*)&wndName);

...
 So, am i doing something wrong, or is this a bug?

You are taking the address of a slice and pass it as if it were a 
C string. You can use toUtf16z for a conversion, but do note the 
limitations of toUtfz.

-Bastiaan

PS this is more a subject for the Learn forum.

=?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:

On Thursday, 8 October 2020 at 19:39:05 UTC, Deen O'Connor wrote:
 ...
 import std.stdio;
 import std.conv;
 import core.sys.windows.windows;

 void main(string[] args) {
     wstring wndName = "x32dbg";
     HWND hWnd = FindWindowW(null, cast(wchar*)&wndName);
     if (hWnd is null) {
         writeln("Error 0x" ~ to!string(GetLastError(), 16) ~ " 
 in FindWindowW()!");
     } else {
         writeln("x32dbg window: 0x" ~ to!string(cast(uint)hWnd, 
 16));
     }
 }

and may be you find interesting this construction:
writefln( "x32dbg window: %X", hWnd );