C#.NET IntPtr Invalid Type

Question

private string getLngLat(string strLAC, string strCID)
    {
        string str;
        try
        {
            HttpWebRequest length = (HttpWebRequest)WebRequest.Create(new Uri("http://www.google.com/glm/mmap"));
            length.Method = "POST";
            int num = Convert.ToInt32(strLAC);
            byte[] numArray = AjaxFrm.PostData(num, Convert.ToInt32(strCID));
            length.ContentLength = (long)((int)numArray.Length);
            length.ContentType = "application/binary";
            length.GetRequestStream().Write(numArray, 0, (int)numArray.Length);
            HttpWebResponse response = (HttpWebResponse)length.GetResponse();
            byte[] numArray1 = new byte[checked((IntPtr)response.ContentLength)]; // ERROR AT HERE
            response.GetResponseStream().Read(numArray1, 0, (int)numArray1.Length);
            if (response.StatusCode != HttpStatusCode.OK)
            {
                str = string.Format("Error {0}", response.StatusCode);
            }
            else
            {
                byte num1 = numArray1[0];
                byte num2 = numArray1[1];
                byte num3 = numArray1[2];
                if ((numArray1[3] << 24 | numArray1[4] << 16 | numArray1[5] << 8 | numArray1[6]) != 0)
                {
                    str = "";
                }
                else
                {
                    double num4 = (double)(numArray1[7] << 24 | numArray1[8] << 16 | numArray1[9] << 8 | numArray1[10]) / 1000000;
                    double num5 = (double)(numArray1[11] << 24 | numArray1[12] << 16 | numArray1[13] << 8 | numArray1[14]) / 1000000;
                    str = string.Format("{0}&{1}", num5, num4);
                }
            }
        }
        catch (Exception exception)
        {
            str = string.Format("Error {0}", exception.Message);
        }
        return str;
    }

byte[] numArray1 = new byte[checked((IntPtr)response.ContentLength)];

here i get the error with

Error 3 Cannot implicitly convert type 'System.IntPtr' to 'int'. An explicit conversion exists (are you missing a cast?)

How come will get this error? how to solve it?

Answer 1

Just specify the array length directly, there's no need to attempt to convert to IntPtr first:

byte[] numArray1 = new byte[response.ContentLength];

IntPtr is a type only intended to hold pointer values, so the usual rules for integral types don't apply. A pointer value is not a sensible array length, so the language designers did not permit using IntPtr to specify an array length.