===请教关于读写字符串的问题===(50分)

用TFileStream,代码如下:

var
stream: TFileStream;
str: string;
len: Integer;
begin
str := 'test string';
len := StrLen(PChar(str));
stream := TFileStream.Create('test', fmCreate);
stream.Write(len, SizeOf(len));
stream.Write(str, len);
stream.Destroy;

stream := TFileStream.Create('test', fmOpenRead);
stream.Read(len, SizeOf(len));
SetLength(str, len);
stream.Read(str, len);
stream.Destroy;
end;

这段代码是错的,
但是要怎么改才对呢?
请大侠详细讲讲,
不才有理了!

var
stream: TFileStream;
str: PChar
// Modified
len: Integer;
begin
str := 'test string';
len := StrLen(str)
// Modified
stream := TFileStream.Create('test', fmCreate);
stream.Write(len, StrLen(len))
// Modified
stream.Write(str, len);
stream.Destroy;

str = ''
// This is additional line

stream := TFileStream.Create('test', fmOpenRead);
stream.Read(len, (len));
SetLength(str, len);
stream.Read(str, len);
stream.Destroy;
end;

吾来灌灌水，

对流操作时要注意流的位置

接受答案了.

我试了一下，这样写的，各位大虾也帮忙看看有什么不妥

var
stream: TFileStream;
str: PChar
// Modified
len: Integer;
begin
str := 'test string';
len := strlen(str)
// Modified
stream := TFileStream.Create('d:/ss.dat', fmCreate);
stream.Write (len,sizeof(integer));
stream.Write(str, len);
stream.free;

str:= ''
// This is additional line

stream := TFileStream.Create('d:/ss.dat', fmOpenRead);
stream.Read(len, sizeof(integer));
stream.Read(str, len);
showmessage(str);
stream.free;
end;
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