IPAddress.IsLoopback(IPAddress) IPAddress.IsLoopback(IPAddress) IPAddress.IsLoopback(IPAddress) IPAddress.IsLoopback(IPAddress) Method

定义

指示指定的 IP 地址是否为环回地址。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

参数

address
IPAddress IPAddress IPAddress IPAddress

IP 地址。An IP address.

返回

如果 address 是环回地址,则为 true;否则为 falsetrue if address is the loopback address; otherwise, false.

示例

下面的代码示例使用IsLoopback方法以确定指定的地址是否为环回地址。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
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 'Main
   
   
   ' 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 'parse 
End Class 'IsLoopbackTest

注解

IsLoopback方法比较addressLoopback,并返回true如果两个 IP 地址相同。The IsLoopback method compares address to Loopback and returns true if the two IP addresses are the same.

对于 IPv4,该IsLoopback方法将返回true窗体的任何 IP 地址 127.X.Y.Z (其中 X、 Y 和 Z 为 0-255 范围内),而不仅仅是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).

适用于