如何将C/C++程序转译成Delphi(八)

3.6. Structures, Records

3.6.1. Simple Structures

C structures are similar to records in Delphi. Structures are usually defined with the typedef keyword, but it's also possible to do it with #define.

The format of a structure declaration is

{Struct|Union} [OptIdentifier] [TagName]
{ FieldDefinitions [; ...]}
[Name [...]]

You can ignore the TagName. It's used in C for subsequent references to the structure.

This is how the fields within a structure are defined:

#define RASENTRYNAMEA struct tagRASENTRYNAMEA



RASENTRYNAMEA



{



    DWORD dwSize;



    CHAR  szEntryName[ RAS_MaxEntryName + 1 ];



};

This C declaration defines a record (structure) named RASENTRYNAMEA. The Delphi-style name would be TRASENTRYNAMEA. This structure contains two fields: the first is named dwSize and has the type DWord. The second field is an array of char with RAS_MaxEntryName + 1 elements.

The Delphi translation:

TYPE



  PRASEntryName = ^TRASEntryName



  TRASEntryName = Record



    dwSize : DWORD;



    szEntryName : Array [0..RAS_MaxEntryName] of Char



  end

Remember, you may not declare the array of char with a range from 0 to RAS_MaxEntryName+1. The reason is, that in C the number of elements is specified, but in Delphi the range of elements. Read more in the chapters about Arrays and Strings.

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3.6.2 Unions in Structures

C unions in structures are comparable to variant parts of records in Delphi. Blocks declared in a union structure are not consecutive but overlaid.

typedef struct _PROCESS_HEAP_ENTRY {



    PVOID lpData;



    DWORD cbData;



    BYTE cbOverhead;



    BYTE iRegionIndex;



    WORD wFlags;



    union {



        struct {



            HANDLE hMem;



            DWORD dwReserved[ 3 ];



        } Block;



        struct {



            DWORD dwCommittedSize;



            DWORD dwUnCommittedSize;



            LPVOID lpFirstBlock;



            LPVOID lpLastBlock;



        } Region;



    };



} PROCESS_HEAP_ENTRY, *LPPROCESS_HEAP_ENTRY, *PPROCESS_HEAP_ENTRY;

This is the translation into Delphi:

type



  PProcessHeapEntry = ^TProcessHeapEntry;



  TProcessHeapEntry = Record



    lpData: Pointer;



    cbData: DWord;



    cbOverhead: Byte;



    iRegionIndex: Byte;



    wFlags: Word;



    case Integer of



      0: (Block: Record



            hMem: Thandle



            Reserved : Array [0..2] of DWord;



          end);



      1: (Region: Record



            dwCommittedSize: DWord;



            dwUnCommittedSize: DWord;



            lpFirstBlock: Pointer;



            lpLastBlock: Pointer



          end);



  end;