1public class IPRegion
 2    {
 3        public static bool IPInRegion(string beginIP, string endIP, string inputIP)
 4        {
 5            IPAddress _beginip;
 6            IPAddress _endip;
 7            IPAddress _inputip;
 8            try
 9            {
10                _beginip = IPAddress.Parse(beginIP);
11                _endip = IPAddress.Parse(endIP);
12                _inputip = IPAddress.Parse(inputIP);
13            }
14            catch (Exception ex)
15            {
16                ErrorHandler.Handle(ex);
17                return false;
18            }
19            if (_beginip == null || _endip == null || _inputip == null) return false;
20
21            byte[] _beginbyte = _beginip.GetAddressBytes();
22            Int64 _beginint = ConvertIPToInt(_beginbyte);
23            byte[] _endbyte = _endip.GetAddressBytes();
24            Int64 _endint = ConvertIPToInt(_endbyte);
25
26            if (_beginint > _endint) return false;
27
28            byte[] _inputtype = _inputip.GetAddressBytes();
29            Int64 _inputint = ConvertIPToInt(_inputtype);
30
31            return (_inputint <= _endint && _inputint >= _beginint);
32        }
33
34        protected static Int64 ConvertIPToInt(byte[] _bytes)
35        {
36            if (_bytes.Length != 4) return 0;
37            string _intstring = "";
38            for (int i = 0; i < _bytes.Length; i++)
39            {
40                _intstring += FormatIPPart(_bytes[i].ToString());
41            }
42            Int64 _outputint;
43            return !Int64.TryParse(_intstring, out _outputint) ? 0 : _outputint;
44        }
45
46        protected static string FormatIPPart(string _ippart)
47        {
48            Regex _regx = new Regex(@"^\d{1,3}$");
49            if (!_regx.IsMatch(_ippart)) return "000";
50            while (_ippart.Length < 3)
51            {
52                _ippart = "0" + _ippart;
53            }
54            return _ippart;
55        }
56    }