System.IndexOutOfRangeException: Index was outside the bounds of the array geocode-api

Question

I am getting index was outside the bounds of the array exception on this line

string strLat = myCoordenates.Results[0].Geometry.Location.Lat.ToString();

This is supposed to pull the latitude from a geocode request and turn it into a string.

Here is the class I am using to Geocode, I got it from here:How to store geocoded address information into the database

using System.Net;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;
using System.Web;

public class GoogleMapsDll
{
    public class GoogleMaps
    {
        /// <summary>
        ///
        /// </summary>
        /// <param name="address"></param>
        /// <returns></returns>
        public static GeoResponse GetGeoCodedResults(string address)
        {
            string url = string.Format(
                    "http://maps.google.com/maps/api/geocode/json?address={0}&region=dk&sensor=false",
                    HttpUtility.UrlEncode(address)
                    );
            var request = (HttpWebRequest)HttpWebRequest.Create(url);
            request.Headers.Add(HttpRequestHeader.AcceptEncoding, "gzip,deflate");
            request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
            DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(GeoResponse));
            var res = (GeoResponse)serializer.ReadObject(request.GetResponse().GetResponseStream());
            return res;
        }
    }

    [DataContract]
    public class GeoResponse
    {
        [DataMember(Name = "status")]
        public string Status { get; set; }

        [DataMember(Name = "results")]
        public CResult[] Results { get; set; }

        [DataContract]
        public class CResult
        {
            [DataMember(Name = "geometry")]
            public CGeometry Geometry { get; set; }

            [DataContract]
            public class CGeometry
            {
                [DataMember(Name = "location")]
                public CLocation Location { get; set; }

                [DataContract]
                public class CLocation
                {
                    [DataMember(Name = "lat")]
                    public double Lat { get; set; }

                    [DataMember(Name = "lng")]
                    public double Lng { get; set; }
                }
            }
        }

        public GeoResponse()
        { }
    }
}

I have read this whole thing (What is an IndexOutOfRangeException / ArgumentOutOfRangeException and how do I fix it?) and parts of it multiple times but I still am not sure how to fix this. I feel like maybe it might be because I am not getting any results from my api request but I am not sure how to tell this for sure.

Answer 1

It's obvious that you get outside the bounds of the array exception because you try to access myCoordenates.Results[0] but myCoordenates.Results has no elements. Always check if myCoordenates.Results is null and if myCoordenates.Results contains any elements before accessing myCoordenates.Results[0]. You also need to check if myCoordenates.Results[0].Geometry is null and if myCoordenates.Results[0].Geometry.Location is null to avoid NullReferenceException, which is also explained here: What is a NullReferenceException and how do I fix it?

if (myCoordenates.Results != null && myCoordenates.Results.Length > 0)
{
    if (myCoordenates.Results[0].Geometry != null
        && myCoordenates.Results[0].Geometry.Location != null)
    {
        string strLat = myCoordenates.Results[0].Geometry.Location.Lat.ToString();
    }
    else
    {
        // logic when myCoordenates.Results[0].Geometry is null or
        // myCoordenates.Results[0].Geometry.Location is null
    }
}
else
{
    // logic when myCoordenates.Results is null or myCoordenates.Results doesn't 
    // have any elements
}

Generally speaking, when myCoordenates.Results is not null you must always check if myCoordenates.Results.Length is larger than n if you want to access myCoordenates.Results[n]. Below is the example if you want to access the fourth element of myCoordenates.Results

if (myCoordenates.Results != null && myCoordenates.Results.Length > 3)
{
    if (myCoordenates.Results[3].Geometry != null
        && myCoordenates.Results[3].Geometry.Location != null)
    {
        string strLat = myCoordenates.Results[3].Geometry.Location.Lat.ToString();
    }
    else
    {
        // logic when myCoordenates.Results[3].Geometry is null or
        // myCoordenates.Results[3].Geometry.Location is null
    }
}
else
{
    // logic when myCoordenates.Results is null or myCoordenates.Results has
    // less than four elements
}