如何到C工會轉換結構裏面德爾福

Question

我需要幫助這個C類聲明轉換爲德爾福：

typedef struct _IO_STATUS_BLOCK { 
    union { 
    NTSTATUS Status; 
    PVOID Pointer_; 
    } ; 
    ULONG_PTR Information; 
} IO_STATUS_BLOCK, *PIO_STATUS_BLOCK; 

Answer 1

從Hardlinks.pas在JCL：

type 
    IO_STATUS_BLOCK = record 
    case integer of 
     0: 
     (Status: NTSTATUS); 
     1: 
     (Pointer: Pointer; 
     Information: ULONG); // 'Information' does not belong to the union! 
    end; 
    // PIO_STATUS_BLOCK = ^IO_STATUS_BLOCK; 

Answer 2

AC聯盟可以翻譯在記錄中有一個case選擇器，這裏的問題是Delphi不允許Case語句之後的任何內容。這可以用一個嵌套的Case語句來解決，就像這樣：

_IO_STATUS_BLOCK = record 
    case Integer of 
     0: (
     case Integer of 
     0: (
      Status: NTSTATUS); 
     1: (
      Pointer_: Pointer); 
     2: (Information: ULONG_PTR)); 
    end; 
    IO_STATUS_BLOCK = _IO_STATUS_BLOCK; 
    PIO_STATUS_BLOCK = ^IO_STATUS_BLOCK; 

/編輯： 爲了使偏移正確的（見下面的註釋）需要填充，修正版本如下。這裏並不提供太多的優勢，但它會如果有更多的領域，甚至工會按照工會第一背後：

_IO_STATUS_BLOCK = record 
    case Integer of 
     0: (
     case Integer of 
      0: (Status: NTSTATUS); 
      1: (Pointer_: Pointer)); 
     1: (
     Pad: DWORD; 
     Information: ULONG_PTR); 
    end; 
    IO_STATUS_BLOCK = _IO_STATUS_BLOCK; 
    PIO_STATUS_BLOCK = ^IO_STATUS_BLOCK; 

/EDIT2： 一個更好的版本是這樣的：

_IO_STATUS_BLOCK = record 
    case Integer of 
     0: (
     Status: NTSTATUS; 
     Pointer_: Pointer); 
     1: (
     case Padding: DWORD of 
      0: (
      Information: ULONG_PTR)); 
    end; 
    IO_STATUS_BLOCK = _IO_STATUS_BLOCK; 
    PIO_STATUS_BLOCK = ^IO_STATUS_BLOCK; 

Answer 3

另外到其他帖子，您可能需要閱讀Pitfalls of Conversion。 Rudy的articles是關於Delphi/C/C++互操作性的信息的金礦。