IPAddress.IsLoopback(IPAddress) 方法

定義

指示指定的 IP 位址是否為回送位址。Indicates whether the specified IP address is the loopback address.

public:
 static bool IsLoopback(System::Net::IPAddress ^ address);
public static bool IsLoopback (System.Net.IPAddress address);
static member IsLoopback : System.Net.IPAddress -> bool
Public Shared Function IsLoopback (address As IPAddress) As Boolean

參數

address
IPAddress

IP 位址。An IP address.

傳回

如果 address 是回送位址,則為 true,否則為 falsetrue if address is the loopback address; otherwise, false.

範例

下列程式碼範例會使用 IsLoopback 方法來判斷指定的位址是否為回送位址。The following code example uses the IsLoopback method to determine whether the specified address is a loopback address.

#using <System.dll>

using namespace System;
using namespace System::Net;
using namespace System::Net::Sockets;

// This method calls the IPAddress::Parse method to check if the
// passed ipAddress parameter is in the correct format.
// Then it checks whether it represents a loopback address.
// Finally, it displays the results.
void parse( String^ ipAddress )
{
   String^ loopBack = " is not a loopback address.";
   try
   {
      
      // Perform syntax check by parsing the address string entered by the user.
      IPAddress^ address = IPAddress::Parse( ipAddress );
      
      // Perform semantic check by verifying that the address is a valid IPv4
      // or IPv6 loopback address.
      if ( IPAddress::IsLoopback( address ) && address->AddressFamily == AddressFamily::InterNetworkV6 )
            loopBack = String::Concat( " is an IPv6 loopback address whose internal format is: ", address, "." );
      else
      if ( IPAddress::IsLoopback( address ) && address->AddressFamily == AddressFamily::InterNetwork )
            loopBack = String::Concat( " is an IPv4 loopback address whose internal format is: ", address, "." );
      
      // Display the results.
      Console::WriteLine( "Your input address: \" {0} \" {1}", ipAddress, loopBack );
   }
   catch ( FormatException^ e ) 
   {
      Console::WriteLine( "FormatException caught!!!" );
      Console::WriteLine( "Source : {0}", e->Source );
      Console::WriteLine( "Message : {0}", e->Message );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "Exception caught!!!" );
      Console::WriteLine( "Source : {0}", e->Source );
      Console::WriteLine( "Message : {0}", e->Message );
   }

}

int main()
{
   array<String^>^args = Environment::GetCommandLineArgs();
   if ( args->Length == 1 )
   {
      
      // No parameters entered. Display program usage.
      Console::WriteLine( "Please enter an IP address." );
      Console::WriteLine( "Usage:   >ipaddress_isloopback any IPv4 or IPv6 address." );
      Console::WriteLine( "Example: >ipaddress_isloopback 127.0.0.1" );
      Console::WriteLine( "Example: >ipaddress_isloopback 0:0:0:0:0:0:0:1" );
   }
   else
      parse( args[ 1 ] );

   
   // Parse the address string entered by the user.
}


using System;
using System.Net;
using System.Net.Sockets;

class IsLoopbackTest
{

  private static void Main(string[] args) 
  {
    
    if (args.Length == 0)
    {
      // No parameters entered. Display program usage.
      Console.WriteLine("Please enter an IP address.");
      Console.WriteLine("Usage:   >ipaddress_isloopback any IPv4 or IPv6 address.");
      Console.WriteLine("Example: >ipaddress_isloopback 127.0.0.1");
      Console.WriteLine("Example: >ipaddress_isloopback 0:0:0:0:0:0:0:1");
      return;
    }
    else
        {
            // Parse the address string entered by the user.
            parse(args[0]);
        }
    }

  // This method calls the IPAddress.Parse method to check if the 
  // passed ipAddress parameter is in the correct format.
  // Then it checks whether it represents a loopback address.
  // Finally, it displays the results.
  private static void parse(string ipAddress)
  {
    string loopBack=" is not a loopback address.";

    try
    {
      // Perform syntax check by parsing the address string entered by the user.
      IPAddress address = IPAddress.Parse(ipAddress);

      // Perform semantic check by verifying that the address is a valid IPv4 
      // or IPv6 loopback address. 
      if(IPAddress.IsLoopback(address)&& address.AddressFamily == AddressFamily.InterNetworkV6)
        loopBack =  " is an IPv6 loopback address " +
                    "whose internal format is: " + address.ToString() + ".";
      else
        if(IPAddress.IsLoopback(address) && address.AddressFamily == AddressFamily.InterNetwork)
          loopBack = " is an IPv4 loopback address " +
                     "whose internal format is: " + address.ToString() + ".";

      // Display the results.
      Console.WriteLine("Your input address: " + "\"" + ipAddress + "\"" + loopBack);
    }

    catch(FormatException e)
    {
      Console.WriteLine("FormatException caught!!!");
      Console.WriteLine("Source : " + e.Source);
      Console.WriteLine("Message : " + e.Message);
    }
    
    catch(Exception e)
    {
      Console.WriteLine("Exception caught!!!");
      Console.WriteLine("Source : " + e.Source);
      Console.WriteLine("Message : " + e.Message);
    }
   }
}
Imports System.Net
Imports System.Net.Sockets

 _

Class IsLoopbackTest
   
   'Entry point which delegates to C-style main Private Function
   Public Overloads Shared Sub Main()
      Main(System.Environment.GetCommandLineArgs())
   End Sub
   
   
   Overloads Private Shared Sub Main(args() As String)
      
       If args.Length = 1 Then
         ' No parameters entered. Display program usage.
         Console.WriteLine("Please enter an IP address.")
         Console.WriteLine("Usage:   >ipaddress_isloopback any IPv4 or IPv6 address.")
         Console.WriteLine("Example: >ipaddress_isloopback 127.0.0.1")
         Console.WriteLine("Example: >ipaddress_isloopback 0:0:0:0:0:0:0:1")
         Return
      ' Parse the address string entered by the user.
      Else
        parse(args(1))
      End If 
   End Sub
   
   
   ' This method calls the IPAddress.Parse method to check whether the 
   ' passed ipAddress parameter is in the correct format.
   ' Then it checks whether it represents a loopback address.
   ' Finally, it displays the results.
   Private Shared Sub parse(ipAdd As String)
      Dim loopBack As String = " is not a loopback address."
      
      Try
         ' Perform syntax check by parsing the address string entered by the user.
         Dim address As IPAddress = IPAddress.Parse(ipAdd)
         
         ' Perform semantic check by verifying that the address is a valid IPv4 
         ' or IPv6 loopback address. 
         If IPAddress.IsLoopback(address) And address.AddressFamily = AddressFamily.InterNetworkV6 Then
            loopBack = " is an IPv6 loopback address " + "whose internal format is: " + address.ToString() + "."
         Else
            If IPAddress.IsLoopback(address) And address.AddressFamily = AddressFamily.InterNetwork Then
               loopBack = " is an IPv4 loopback address " + "whose internal format is: " + address.ToString() + "."
            End If
         End If 
         ' Display the results.
         Console.WriteLine(("Your input address: " + """" + ipAdd + """" + loopBack))
      
      Catch e As FormatException
         Console.WriteLine("FormatException caught!!!")
         Console.WriteLine(("Source : " + e.Source))
         Console.WriteLine(("Message : " + e.Message))
      
      Catch e As Exception
         Console.WriteLine("Exception caught!!!")
         Console.WriteLine(("Source : " + e.Source))
         Console.WriteLine(("Message : " + e.Message))
      End Try
   End Sub
End Class

備註

IsLoopback 方法會比較 addressLoopback,並在兩個 IP 位址相同時傳回 trueThe IsLoopback method compares address to Loopback and returns true if the two IP addresses are the same.

就 IPv4 而言,IsLoopback 方法會針對格式為 127. X. Z 的任何 IP 位址傳回 true (其中 X、Y 和 Z 在範圍0-255 中),而不只是 Loopback (127.0.0.1)。In the case of IPv4, that the IsLoopback method returns true for any IP address of the form 127.X.Y.Z (where X, Y, and Z are in the range 0-255), not just Loopback (127.0.0.1).

適用於