function TForm44.find(name: string): Boolean;
var
   WSAData:TWSAData;
   HostEnt:PHostEnt;
begin
  Result:=True;
  WSAStartup(2,WSAData);
  HostEnt:=gethostbyname(PCHar(Name));
  if HostEnt=nil then
  Result:=False;
  WSACleanup;
end;procedure TForm44.Button1Click(Sender: TObject);
var cIP:string;
begin
  if find(edit1.Text)=true then
  begin
    showmessage(edit1.Text+'在局域网上');
    button2.Enabled:=true;
    cIP:=format('%d.%d.%d.%d',[byte(h_addr^[0]),byte(h_addr^[1]),byte  (h_addr^[2]),byte(h_addr^[3])]);
//编译到这时,提示[Error] Unit44.pas(65): Undeclared identifier: 'h_addr'
    memo1.Text:=edit1.Text+'的IP是'+cIP;
  end
  else begin
    showmessage(edit1.text+'不在局域网上');
    button2.Enabled:=false;
    memo1.Text:='对不起,得不到IP';     
  end;
end;