如何检测计算机是否连上Internet及怎样获取本机IP？

Question

function TForm1.CheckOffline: boolean;
var
  ConnectState: DWORD;
  StateSize: DWORD;
begin
  ConnectState:= 0;
  StateSize:= SizeOf(ConnectState);
  result:= false;
  if InternetQueryOption(nil, INTERNET_OPTION_CONNECTED_STATE, @ConnectState, StateSize) then  if (ConnectState and INTERNET_STATE_DISCONNECTED) <> 2 then result:= true;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
  if CheckOffline then
  edit1.text:= 'Connect To ISP'
  else
  edit1.text:= 'Disconnect To ISP';
end;

Answer 1

uses WinInet;procedure TForm1.Button1Click(Sender: TObject);  function GetOnlineStatus : Boolean;
  var ConTypes : Integer;
  begin
    ConTypes := INTERNET_CONNECTION_MODEM + INTERNET_CONNECTION_LAN + INTERNET_CONNECTION_PROXY;
    if (InternetGetConnectedState(@ConTypes, 0) = False)
     then Result := False
     else Result := True;
  end;begin
 if GetOnlineStatus then
   ShowMessage(' Connected')
   else ShowMessage(' not Connected');
end;

Answer 2

下面的代码可以实现你的要求。如果还想更深入了解你可以去 http://delphix.126.com
的控件仓库中下载netusers.zip，他的源码写的很好。 procedure TForm1.Button1Click(Sender: TObject);
var Ip,IpStr:string;  ch:array[1..32]of char;  i:integer;
    WSData:TWSAData;  MyHost:PHostEnt;
begin
   if WSAstartup(2,WSData)<>0 then
      begin
         ShowMessage('没有成功返回！');
         Halt(2);
      end;
   try
      if getHostName(@ch[1],32)<>0 then
         begin
            ShowMessage('没有成功返回！');
            Halt(3);
         end;
   except
      ShowMessage('没有成功返回！');
      Halt(3);
   end;
   MyHost:=GetHostByName(@ch[1]);
   if MyHost=NIL then
      begin
         ShowMessage('没有成功返回！');
         Halt(4);
      end
   else
      begin
         for i:=1 to 4 do
            begin
               Ip:=inttostr(Ord(MyHost.h_addr^[i-1]));
               ShowMessage('IP分段地址为:'+Ip);
               IPStr:=IPStr+Ip;
               if i<4 then IPStr:=IPStr+'.'
               else  ShowMessage('IP地址为:'+IPStr);
            end;
      end;
end;