NativeXml (11)：浮点数的有效位数

uses NativeXml; 

 

procedure TForm1.Button1Click(Sender: TObject); 

var 

  xml: TNativeXml; 

  fVal: Double; 

begin 

  fVal := 123.456789; 

 

  xml := TNativeXml.CreateName('List'); 

  xml.XmlFormat := xfReadable; 

 

  //xml.FloatSignificantDigits := ; 

  with xml.Root.NodeNew('item') do begin 

    WriteString('Name', 'AAA'); 

    WriteFloat('Weight', fVal); 

  end; 

 

  xml.FloatSignificantDigits := 5; 

  with xml.Root.NodeNew('item') do begin 

    WriteString('Name', 'BBB'); 

    WriteFloat('Weight', fVal); 

  end; 

 

  xml.FloatSignificantDigits := 1; 

  with xml.Root.NodeNew('item') do begin 

    WriteString('Name', 'CCC'); 

    WriteFloat('Weight', fVal); 

  end; 

 

  xml.FloatSignificantDigits := 9; 

  with xml.Root.NodeNew('item') do begin 

    WriteString('Name', 'DDD'); 

    WriteFloat('Weight', fVal); 

  end; 

 

  ShowMessage(xml.Root[0][1].Value); //123.457 

  ShowMessage(xml.Root[1][1].Value); //123.46 

  ShowMessage(xml.Root[2][1].Value); //100 

  ShowMessage(xml.Root[3][1].Value); //123.456789 

  Memo1.Text := xml.WriteToString; 

  xml.Free; 

end; 

{*************************************** 

<?xml version="1.0" encoding="UTF-8"?> 

<List> 

	<item> 

		<Name>AAA</Name> 

		<Weight>123.457</Weight> 

	</item> 

	<item> 

		<Name>BBB</Name> 

		<Weight>123.46</Weight> 

	</item> 

	<item> 

		<Name>CCC</Name> 

		<Weight>100</Weight> 

	</item> 

	<item> 

		<Name>DDD</Name> 

		<Weight>123.456789</Weight> 

	</item> 

</List> 

*****************************************}

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