如主題.

你好：     Null = 0    

NIL;

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你好：     補充說明，以下列宣告為例，如果屬於指標型態可用 nil 或 0 帶入， 如果是數值型態則僅能帶入 0 。 API 原型宣告 int MessageBox( HWND hWnd, // handle of owner window LPCTSTR lpText, // address of text in message box LPCTSTR lpCaption, // address of title of message box UINT uType // style of message box ); Parameters hWnd Identifies the owner window of the message box to be created. If this parameter is NULL, the message box has no owner window. lpText Points to a null-terminated string containing the message to be displayed. lpCaption Points to a null-terminated string used for the dialog box title. If this parameter is NULL, the default title Error is used. uType Specifies a set of bit flags that determine the contents and behavior of the dialog box. This parameter can be a combination of flags from the following groups of flags. Specify one of the following flags to indicate the buttons contained in the message box: Delphi 宣告 function MessageBox( hWnd: HWND; lpText, lpCaption: PChar; uType: UINT): Integer; stdcall;