{{DISPLAYTITLE:_WINDOWHANDLE}}
The [[_WINDOWHANDLE]] function returns the window handle assigned to the current program by the OS. Windows-only.


{{PageSyntax}}
: {{Parameter|hwnd&&}} = [[_WINDOWHANDLE]]


{{PageDescription}}
* The result is an [[_INTEGER64]] number assigned by Windows to your running program.
* Use it to make [[Windows Libraries|API calls]] that require a window handle to be passed.
* [[Keywords_currently_not_supported_by_QB64#Keywords_Not_Supported_in_Linux_or_MAC_OSX_versions|Not available in Linux or macOS]].


==Availability==
* '''Build 20170924/68'''.


{{PageExamples}}
''Example:'' Showing the system-default message box in Windows.
{{CodeStart}} '' ''
'Message Box Constant values as defined by Microsoft (MBType)
{{Cl|CONST}} MB_OK& = 0                'OK button only
{{Cl|CONST}} MB_OKCANCEL& = 1          'OK & Cancel 
{{Cl|CONST}} MB_ABORTRETRYIGNORE& = 2  'Abort, Retry & Ignore
{{Cl|CONST}} MB_YESNOCANCEL& = 3       'Yes, No & Cancel
{{Cl|CONST}} MB_YESNO& = 4             'Yes & No
{{Cl|CONST}} MB_RETRYCANCEL& = 5       'Retry & Cancel
{{Cl|CONST}} MB_CANCELTRYCONTINUE& = 6 'Cancel, Try Again & Continue
{{Cl|CONST}} MB_ICONSTOP& = 16         'Error stop sign icon
{{Cl|CONST}} MB_ICONQUESTION& = 32     'Question-mark icon
{{Cl|CONST}} MB_ICONEXCLAMATION& = 48  'Exclamation-point icon
{{Cl|CONST}} MB_ICONINFORMATION& = 64  'Letter i in a circle icon
{{Cl|CONST}} MB_DEFBUTTON1& = 0        '1st button default(left)
{{Cl|CONST}} MB_DEFBUTTON2& = 256      '2nd button default
{{Cl|CONST}} MB_DEFBUTTON3& = 512      '3rd button default(right)
{{Cl|CONST}} MB_APPLMODAL& = 0         'Message box applies to application only
{{Cl|CONST}} MB_SYSTEMMODAL& = 4096    'Message box on top of all other windows
{{Cl|CONST}} MB_SETFOCUS& = 65536      'Set message box as focus
{{Cl|CONST}} IDOK& = 1                 'OK button pressed
{{Cl|CONST}} IDCANCEL& = 2             'Cancel button pressed
{{Cl|CONST}} IDABORT& = 3              'Abort button pressed
{{Cl|CONST}} IDRETRY& = 4              'Retry button pressed
{{Cl|CONST}} IDIGNORE& = 5             'Ignore button pressed
{{Cl|CONST}} IDYES& = 6                'Yes button pressed
{{Cl|CONST}} IDNO& = 7                 'No button pressed
{{Cl|CONST}} IDTRYAGAIN& = 10          'Try again button pressed
{{Cl|CONST}} IDCONTINUE& = 1           'Continue button pressed
'----------------------------------------------------------------------------------------

{{Cl|DECLARE LIBRARY|DECLARE DYNAMIC LIBRARY}} "user32"
{{Cl|FUNCTION}} MessageBoxA& ({{Cl|BYVAL}} hwnd {{Cl|AS}} {{Cl|LONG}}, Message {{Cl|AS}} {{Cl|STRING}}, Title {{Cl|AS}} {{Cl|STRING}}, {{Cl|BYVAL}} MBType {{Cl|AS}} {{Cl|_UNSIGNED}} {{Cl|LONG}})
{{Cl|DECLARE LIBRARY|END DECLARE}}

DO
  msg& = 0: icon& = 0: DB& = 0
  {{Cl|INPUT}} "Enter Message Box type(0 to 6 other Quits): ", BOX&
  {{Cl|IF...THEN|IF}} BOX& < 0 {{Cl|OR (boolean)|OR}} BOX& > 6 {{Cl|THEN}} {{Cl|EXIT DO}}

  {{Cl|INPUT}} "Enter Icon&(0=none, 1=stop, 2=?, 3=!, 4=info): ", Icon&
  
  {{Cl|IF...THEN|IF}} BOX& {{Cl|THEN}} {{Cl|INPUT (file mode)|INPUT}} "Enter Default Button(1st, 2nd or 3rd): ", DB&
  {{Cl|IF...THEN|IF}} DB& {{Cl|THEN}} DB& = DB& - 1     'adjust value to 0, 1, or 2
  msg& = MsgBox&("Box Title", "Box text message", BOX&, Icon&, DB&, 4096) 'on top of all windows

  {{Cl|PRINT}} "Button ="; msg&
{{Cl|LOOP}}
{{Cl|END}}

{{Cl|FUNCTION}} MsgBox& (Title$, Message$, BoxType&, Icon&, DBtn&, Mode&)
{{Cl|SELECT CASE}} Icon&
  {{Cl|CASE}} 1: Icon& = MB_ICONSTOP&          'warning X-sign icon
  {{Cl|CASE}} 2: Icon& = MB_ICONQUESTION&      'question-mark icon
  {{Cl|CASE}} 3: Icon& = MB_ICONEXCLAMATION&   'exclamation-point icon
  {{Cl|CASE}} 4: Icon& = MB_ICONINFORMATION&   'lowercase letter i in circle
  {{Cl|CASE ELSE}}: Icon& = 0 'no icon
{{Cl|END SELECT}}
{{Cl|IF...THEN|IF}} BoxType& > 0 {{Cl|AND (boolean)|AND}} DBtn& > 0 {{Cl|THEN}} 'set default button as 2nd(256) or 3rd(512)
  {{Cl|SELECT CASE}} BoxType&    
    {{Cl|CASE}} 2, 3, 6
     {{Cl|IF...THEN|IF}} DBtn& = 2 {{Cl|THEN}} Icon& = Icon& + MB_DEFBUTTON3& {{Cl|ELSE}} Icon& = Icon& + MB_DEFBUTTON2& '3 button
    {{Cl|CASE ELSE}}: Icon& = Icon& + MB_DEFBUTTON2& '2nd button default
  {{Cl|END SELECT}}
{{Cl|END IF}}
Focus& = MB_SetFocus&
MsgBox& = MessageBoxA&({{Cl|_WINDOWHANDLE}}, Message$, Title$, BoxType& + Icon& + Mode& + Focus&) 'focus on button
{{Cl|END FUNCTION}} '' ''
{{CodeEnd}}
:''Explanation:'' Notice how the call to the external dynamic library function MessageBoxA& passes _WINDOWHANDLE to the API and how the message box shown is created as a child of your program's window, not allowing the main window to be manipulated while the message box is open.

{{PageSeeAlso}}
* [[_WINDOWHASFOCUS]]
* [[Windows Libraries]]


{{PageNavigation}}
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