Store String Array In appSettings?

For strings it is easy, simply add the following to your web.config file:

<add key="myStringArray" value="fred,Jim,Alan" />

and then you can retrieve the value into an array as follows:

var myArray = ConfigurationManager.AppSettings["myStringArray"].Split(',');

ASP.Net Core supports it binding a list of strings or objects.

For strings as mentioned, it is possible to retrieve it through AsEnumerable().

Or a list of objects via Get<List<MyObject>>(). The sample is below.

appsettings.json:

{
 ...
   "my_section": {
     "objs": [
       {
         "id": "2",
         "name": "Object 1"
       },
       {
         "id": "2",
         "name": "Object 2"
       }
     ]
   }
 ...
}

Class to represent the object

public class MyObject
{
    public string Id { get; set; }
    public string Name { get; set; }
}

Code to retrieve from appsettings.json

Configuration.GetSection("my_section:objs").Get<List<MyObject>>();

For integers I found the following way quicker.

First of all create a appSettings key with integer values separated by commas in your app.config.

<add key="myIntArray" value="1,2,3,4" />

Then split and convert the values into int array by using LINQ

int[] myIntArray =  ConfigurationManager.AppSettings["myIntArray"].Split(',').Select(n => Convert.ToInt32(n)).ToArray();

You could use the AppSettings with a System.Collections.Specialized.StringCollection.

var myStringCollection = Properties.Settings.Default.MyCollection;
foreach (String value in myStringCollection)
{ 
    // do something
}

Each value is separated by a new line.

Here's a screenshot (german IDE but it might be helpful anyway)