XmlConvert.ToDouble(String) 方法

定義

命名空間:

System.Xml

組件:

System.Xml.ReaderWriter.dll

來源:

XmlConvert.cs

將 String 轉換成對等的 Double。

public:
 static double ToDouble(System::String ^ s);

public static double ToDouble (string s);

static member ToDouble : string -> double

Public Shared Function ToDouble (s As String) As Double

參數

s

String

要轉換的字串。

傳回

Double

字串的對等 Double。

例外狀況

ArgumentNullException

s 為 null。

FormatException

s 的格式不正確。

OverflowException

s 代表小於 Double.MinValue 或大於 Double.MaxValue的數位。

範例

下列範例會使用 ToDouble 和 ToDateTime 來讀取強型別資料。

#using <System.dll>
#using <System.xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
int main()
{
   XmlTextReader^ reader = gcnew XmlTextReader( "orderData.xml" );
   
   //Parse the file and pull out the order date and price.
   while ( reader->Read() )
   {
      if ( reader->NodeType == XmlNodeType::Element )
      {
         if ( reader->Name->Equals( "order" ) )
         {
            DateTime orderDate = XmlConvert::ToDateTime( reader->GetAttribute( "date" ) );
            Console::WriteLine( "order date: {0}", orderDate.ToString() );
         }
         else
         if ( reader->Name->Equals( "price" ) )
         {
            Double price = XmlConvert::ToDouble( reader->ReadInnerXml() );
            Console::WriteLine( "price: {0}", price );
         }
      }
   }

   
   //Close the reader.
   reader->Close();
}

using System;
using System.IO;
using System.Xml;

public class Sample
{

  public static void Main()
  {
    XmlTextReader reader = new XmlTextReader("orderData.xml");

    //Parse the file and pull out the order date and price.
    while (reader.Read()){
       if (reader.NodeType==XmlNodeType.Element){
         switch(reader.Name){
           case "order":
             DateTime orderDate = XmlConvert.ToDateTime(reader.GetAttribute("date"));
             Console.WriteLine("order date: {0}", orderDate.ToString());
             break;
           case "price":
             Double price = XmlConvert.ToDouble(reader.ReadInnerXml());
             Console.WriteLine("price: {0}", price.ToString());
             break;
         }
       }
    }

    //Close the reader.
    reader.Close();
  }
}

Imports System.IO
Imports System.Xml

public class Sample

  public shared sub Main()
  
    Dim reader as XmlTextReader = new XmlTextReader("orderData.xml")

    'Parse the file and pull out the order date and price.
    while (reader.Read())
       if (reader.NodeType=XmlNodeType.Element)
         select case reader.Name
           case "order":
             Dim orderDate as DateTime = XmlConvert.ToDateTime(reader.GetAttribute("date"))
             Console.WriteLine("order date: {0}", orderDate.ToString())
           case "price":
             Dim price as Double = XmlConvert.ToDouble(reader.ReadInnerXml())
             Console.WriteLine("price: {0}", price.ToString())
         end select
       end if
    end while

    'Close the reader.
    reader.Close()  
  end sub
end class

此範例會使用 檔案 orderData.xml ，作為輸入。

<order date="2001-05-03">
  <orderID>367A54</orderID>
  <custID>32632</custID>
  <price>19.95</price>
</order>

備註

如果 s 是 INF 或 -INF，這個方法會分別傳回 Double.PositiveInfinity 或 Double.NegativeInfinity。

另請參閱

• PositiveInfinity
• NegativeInfinity