System.Net.WebUtility.UrlEncode C# (CSharp) Method

        public static string UrlEncode(string value)
        {
            if (string.IsNullOrEmpty(value))
                return value;

            int safeCount = 0;
            int spaceCount = 0;
            for (int i = 0; i < value.Length; i++)
            {
                char ch = value[i];
                if (IsUrlSafeChar(ch))
                {
                    safeCount++;
                }
                else if (ch == ' ')
                {
                    spaceCount++;
                }
            }

            int unexpandedCount = safeCount + spaceCount;
            if (unexpandedCount == value.Length)
            {
                if (spaceCount != 0)
                {
                    // Only spaces to encode
                    return value.Replace(' ', '+');
                }

                // Nothing to expand
                return value;
            }

            int byteCount = Encoding.UTF8.GetByteCount(value);
            int unsafeByteCount = byteCount - unexpandedCount;
            int byteIndex = unsafeByteCount * 2;

            // Instead of allocating one array of length `byteCount` to store
            // the UTF-8 encoded bytes, and then a second array of length 
            // `3 * byteCount - 2 * unexpandedCount`
            // to store the URL-encoded UTF-8 bytes, we allocate a single array of
            // the latter and encode the data in place, saving the first allocation.
            // We store the UTF-8 bytes to the end of this array, and then URL encode to the
            // beginning of the array.
            byte[] newBytes = new byte[byteCount + byteIndex];
            Encoding.UTF8.GetBytes(value, 0, value.Length, newBytes, byteIndex);
            
            GetEncodedBytes(newBytes, byteIndex, byteCount, newBytes);
            return Encoding.UTF8.GetString(newBytes);
        }