Lấy địa chỉ IP trong lập trình bằng một số ngôn ngữ thông dụng

using System;
using System.Net;
 
namespace GetIPCS
{
 ///
 /// Gets IP addresses of the local machine
 ///
 class classGetIPCS
 {
  ///
  /// Gets IP addresses of the local machine
  ///
  [STAThread]
  static void Main(string[] args)
  {
   // Get host name
   String strHostName = Dns.GetHostName();
   Console.WriteLine("Host Name: " + strHostName);
 
   // Find host by name
   IPHostEntry iphostentry = Dns.GetHostByName(strHostName);
 
   // Enumerate IP addresses
   int nIP = 0;
   foreach(IPAddress ipaddress in iphostentry.AddressList)
   {
    Console.WriteLine("IP #" + ++nIP + ": " +
                      ipaddress.ToString());
   }
  }
 }
}

uses  Winsock;
 
function getIPs: Tstrings;
type
  TaPInAddr = array[0..10] of PInAddr;
  PaPInAddr = ^TaPInAddr;
var
  phe: PHostEnt;
  pptr: PaPInAddr;
  Buffer: array[0..63] of Char;
  I: Integer;
  GInitData: TWSAData;
begin
  WSAStartup($101, GInitData);
  Result := TstringList.Create;
  Result.Clear;
  GetHostName(Buffer, SizeOf(Buffer));
  phe := GetHostByName(buffer);
  if phe = nil then Exit;
  pPtr := PaPInAddr(phe^.h_addr_list);
  I    := 0;
  while pPtr^[I] <> nil do
  begin
    Result.Add(inet_ntoa(pptr^[I]^));
    Inc(I);
  end;
  WSACleanup;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
  ShowMessage(GetIps.text);
end;

Private Sub IPAddress()
'To get local address
	Dim LocalHostName As String
	Dim i As Integer
	LocalHostName = Dns.GetHostName()
	Dim ipEnter As IPHostEntry = Dns.GetHostByName(LocalHostName)
	Dim IpAdd() As IPAddress = ipEnter.AddressList
	For i = 0 To IpAdd.GetUpperBound(0)
	Next
End Sub

// Borland C++ 5.0: bcc32.cpp getlocalip.cpp
// Visual C++ 5.0: cl getlocalip.cpp wsock32.lib
//
// This sample program is hereby placed in the public domain.
 
#include
#include 
 
int doit(int, char **)
{
    char ac[80];
    if (gethostname(ac, sizeof(ac)) == SOCKET_ERROR) {
        cerr < < "Error " << WSAGetLastError() <<
                " when getting local host name." << endl;
        return 1;
    }
    cout << "Host name is " << ac << "." << endl;
 
    struct hostent *phe = gethostbyname(ac);
    if (phe == 0) {
        cerr << "Yow! Bad host lookup." << endl;         return 1;     }     for (int i = 0; phe->h_addr_list[i] != 0; ++i) {
        struct in_addr addr;
        memcpy(&addr, phe->h_addr_list[i], sizeof(struct in_addr));
        cout < < "Address " << i << ": " << inet_ntoa(addr) << endl;
    }
 
    return 0;
}
 
int main(int argc, char *argv[])
{
    WSAData wsaData;
    if (WSAStartup(MAKEWORD(1, 1), &wsaData) != 0) {
        return 255;
    }
 
    int retval = doit(argc, argv);
 
    WSACleanup();
 
    return retval;
}
}

import java.net.*;
import java.io.*;
 
public class GetIPAddress
{
	public static void main(String [] args)
	{
		try
		{
			InetAddress thisIp =InetAddress.getLocalHost();
			System.out.println("IP:"+thisIp.getHostAddress());
		}
		catch(Exception e)
		{
			e.printStackTrace();
		}
	}
}

string ip;
ip=Request.ServerVariables("HTTP_X_FORWARDED_FOR");
if(ip==string.Empty)
{
ip=Request.ServerVariables("REMOTE_ADDR");
}

$ip=$_SERVER['REMOTE_ADDR'];

<% Response.Write Request.ServerVariables("REMOTE_ADDR") %>