Code-Validator：验证IPv4地址

using System;

namespace Sp.Common
{
    public class ValidatorHelper
    {
        /// <summary>  
        /// 验证IPv4地址  
        /// [第一位和最后一位数字不能是0或255；允许用0补位]  
        /// </summary>  
        /// <param name="input">待验证的字符串</param>  
        /// <returns>是否匹配</returns>  
        public static bool IsIPv4(string input)
        {
            //string pattern = @"^(25[0-4]|2[0-4]\d]|[01]?\d{2}|[1-9])\.(25[0-5]|2[0-4]\d]|[01]?\d?\d)\.(25[0-5]|2[0-4]\d]|[01]?\d?\d)\.(25[0-4]|2[0-4]\d]|[01]?\d{2}|[1-9])$";  
            //return IsMatch(input, pattern);  
            string[] IPs = input.Split(‘.‘);
            if (IPs.Length != 4)
                return false;
            int n = -1;
            for (int i = 0; i < IPs.Length; i++)
            {
                if (i == 0 || i == 3)
                {
                    if (int.TryParse(IPs[i], out n) && n > 0 && n < 255)
                        continue;
                    else
                        return false;
                }
                else
                {
                    if (int.TryParse(IPs[i], out n) && n >= 0 && n <= 255)
                        continue;
                    else
                        return false;
                }
            }
            return true;
        }

    }
}