德爾福複製的MemoryStream到動態數組

Question

您好請我這個包裝記錄：

type 
TMyRecord = packed record 
    BufSize: Word; 
    TargetUser:array[0..80] of char; 
    StreamHolder: Byte; 
    end; 
    PMyRecord = ^TMyRecord; 

//我想將MemoryStream保存到StreamHolder 請看下面我的方法：

Procedure AddToRec(ATargetUser:String); 
var 
MyRecord: PMyRecord; 
Strm:TMemoryStream; 
Size: Integer; 
begin 
Strm:=TMemoryStream.Create; 
try 
Strm.LoadFromFile('myFile.dat'); 
Strm.position:=0; 
Size:=Strm.size; 
GetMem(MyRecord,Size); 
ZeroMemory(MyRecord,Size); 
MyRecord.BufSize := Size; 
StrCopy(MyRecord.TargetUser,PChar(ATargetUser)); 

// here how could i copy the Strm into the StreamHolder ? 

//SendMyBuffer(MyRecord,Size); 

finally 
Strm.free; 
end; 
end; 

那麼請我如何將Strm複製到StreamHolder？

千恩萬謝

Answer 1

你似乎想，將整個物流複製到@MyRecord.StreamHolder。是這樣做的：

Strm.ReadBuffer(MyRecord.StreamHolder, Size); 

你還需要改變你的GetMem分配足夠的內存。

GetMem(MyRecord, Size + SizeOf(MyRecord^) - SizeOf(MyRecord.StreamHolder)); 

或許更優雅：

GetMem(MyRecord, Size + Integer(@PMyRecord(nil)^.StreamHolder)); 

既然這樣你的代碼並沒有考慮這StreamHolder之前出現的創紀錄的那部分。

Answer 2

爲什麼不持有

StreamHolder: Byte; 

爲

StreamHolder: tMemoryStream; 

和改變過程

var 
    MyRecord: PMyRecord; 
begin 
    GetMem(MyRecord,SizeOf(pMyRecord)); 
    myRecord.StreamHolder := TMemoryStream.Create; 
    try 
    myRecord.StreamHolder.LoadFromFile('myFile.dat'); 
    //Strm.position:=0; 
    //Size:=Strm.size; 
    //ZeroMemory(MyRecord,Size); 
    //MyRecord.BufSize := Size; 
    StrCopy(MyRecord.TargetUser,PChar(ATargetUser)); 
    finally 
    // no free in here... free the streamholder whenever you get rid of MyRecord... 
    end ;