问一个delphi的问题，急急急，在线等！

Question

在dephi中，如果有一文件为100字节长，为二进制，怎么按字节读起，比如先读20字节，然后再读 30字节，一直读完。谢谢了

Answer 1

//稍稍修改一下就可以了var
  F1, F2: File;
  NumRead, NumWritten: Integer;
  Buf: array[0..19] of Char;
begin
    AssignFile(F1, 'test1.bin');
    Reset(F1, 1); // Record size set to 1 
    AssignFile(F2, 'test2.bin');
    Rewrite(F2, 1); // d.o.    repeat
        BlockRead(F1, Buf, SizeOf(Buf), NumRead);
        BlockWrite(F2, Buf, NumRead, NumWritten);
    until (NumRead = 0) or (NumWritten <> NumRead);    CloseFile(F2);
    CloseFile(F1);end;

Answer 2

var
  UnTypedFile: File;
  Buffer: array[0..20] of byte;
  NumRecsRead: Integer;
begin
  AssignFile(UnTypedFile, ‘SOMEFILE.DAT’);
  Reset(UnTypedFile);
  try
    BlockRead(UnTypedFile, Buffer, 1, NumRecsRead);//读20字节
             ..........//和上面类似 
  finally
    CloseFile(UnTypedFile);
  end;
end;

Answer 3

var
        fs:TFileStream;
        buf:array[0..100] of char;
begin
        if fileexists(extractfilepath(application.ExeName)+'TopicView.txt') then
        begin
                try
                fs:=TFileStream.Create(extractfilepath(application.ExeName)+'TopicView.txt',fmOpenRead);
                fs.Position:=0;
                if fs.Size>20 then
                begin
                   fs.Read(buf,20);
                   edit1.Text:=buf;
                end;
                if fs.size>fs.Position +30 then
                begin
                     fs.Read(buf,20);
                   edit2.Text:=buf;
                end;
                finally
                        fs.Free;
                end;
        end;end;