build query string

using System;
using System.Collections.Generic;
using System.Text;
using System.Web;

namespace ARF.Web.Utility
{
    public class XslFunctions
    {
        public static string BuildQueryString(string newValues, string s1)
        {
            return BuildQueryString(newValues, s1, "", "", "");
        }

        public static string BuildQueryString(string newValues, string s1, string s2)
        {
            return BuildQueryString(newValues, s1, s2, "", "");
        }

        public static string BuildQueryString(string newValues, string s1, string s2, string s3)
        {
            return BuildQueryString(newValues, s1, s2, s3, "");
        }

        public static string BuildQueryString(string newValues, string s1, string s2, string s3, string s4)
        {
            StringBuilder oResult = new StringBuilder("?" + newValues);

            string[] remove = new string[] { s1, s2, s3, s4 };

            List<string> oKeysToRemove = new List<string>(remove);

            System.Collections.Specialized.NameValueCollection qs = HttpContext.Current.Request.QueryString;

            foreach (string sKey in qs.AllKeys)
            {
                if (!oKeysToRemove.Contains(sKey.ToLower()) && !oKeysToRemove.Contains(sKey))
                    oResult.Append(string.Format("&{0}={1}", sKey, qs[sKey]));
            }

            return oResult.ToString();
        }
    }
}