Delphi- 如何在保存前删除非 ANSI（不可打印）字符？

Question

有人可以指导我以某种方式扩展此过程，以便在将流保存到文件之前删除所有不可打印字符或替换为 SPACE 吗？字符串从二进制文件中读取，最大大小为 1 MB。我的程序：

var
  i : Word;
  FileName : TFileName;
  SizeofFiles,posi : Integer;
  fs, sStream: TFileStream;
  SplitFileName: String;
begin
  ProgressBar1.Position := 0;
  FileName:= lblFilePath.Caption;
  SizeofFiles := StrToInt(edt2.Text)  ;
  posi := StrToInt(edt1.text) ;
  fs := TFileStream.Create(FileName, fmOpenRead or fmShareDenyWrite);
  try
             fs.Position := Posi ;
    begin
      SplitFileName := ChangeFileExt(FileName, '.'+ FormatFloat('000', i));
      sStream := TFileStream.Create(SplitFileName, fmCreate or fmShareExclusive);
      try
        if fs.Size - fs.Position < SizeofFiles then
          SizeofFiles := fs.Size - fs.Position;
        sStream.CopyFrom(fs, SizeofFiles);
        ProgressBar1.Position := Round((fs.Position / fs.Size) * 100);
      finally
        sStream.Free;
      end;
    end;
  finally
    fs.Free;
  end;
end;

Answer 1

您将无法再使用 TStream.CopyFrom()。您必须从源 TStream Read(Buffer)() 到本地字节数组，从该数组中删除您不想要的任何内容，然后 Write(Buffer)() 将剩余字节发送到目标 TStream.

Answer 2

这是一个简单的演示，可以满足您的需求：

const
    SrcFileName   : String = 'Test.txt';
    DstFileName   : String = 'TestResult.txt';
    StartPosition : Int64  = 50;

procedure TForm1.Button1Click(Sender: TObject);
var
    FS  : TFileStream;
    Buf : TBytes;
    I   : Integer;
begin
    // Read the source file from starting position
    FS := TFileStream.Create(SrcFileName, fmOpenRead or fmShareDenyWrite);
    try
        FS.Position := StartPosition;
        SetLength(Buf, FS.Size - FS.Position);
        FS.Read(Buf[0], Length(Buf));
    finally
        FreeAndNil(FS);
    end;

    // Replace all non printable character by a space
    // Assume file content is ASCII characters
    for I := 0 to Length(Buf) - 1 do begin
        // You may want to make a more complex test for printable of not
        if (Ord(Buf[I]) < Ord(' ')) or (Ord(Buf[I]) > 126) then
            Buf[I] := Ord(' ');
    end;

    // Write destination file
    FS := TFileStream.Create(DstFileName, fmCreate);
    try
        FS.Write(Buf[0], Length(Buf));
    finally
        FreeAndNil(FS);
    end;
end;

此代码假定文件是纯 ASCII 文本，并且 ASCII 代码低于 32 (space) 或高于 126 的每个字符均不可打印。欧洲语言可能并非如此。您可以轻松调整测试以满足您的需求。

源文件也可以是 Unicode（16 位字符）。您应该使用由 Unicode 字符或 16 位整数 (Word) 组成的缓冲区。并调整可打印的测试。

也可以是UTF8...

Delphi- 如何在保存前删除非 ANSI（不可打印）字符？

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