Return empty array instead of null

Question

I created Settings class which I use to edit my application by .ini file. My Settings.ini file looks like this:

[ACCOUNT]
login=xyz
password=xyz
locations=1,2,5,8

Now I am getting theese values like this:

class Settings {
    public static IniFile Config = new IniFile(Directory.GetCurrentDirectory() + @"\Settings.ini");
    public static string Login { get { return Config.Read("login", "ACCOUNT"); } set { Config.Write("login", "ACCOUNT"); } }
    public static string Password { get { return Config.Read("password", "ACCOUNT"); } set { Config.Write("password", "ACCOUNT"); } }
    public static int[] Locations { get { return Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s)); } set { Config.Write("locations", "ACCOUNT"); } }
}

The problem is, when my Settings.ini file has empty locations:

locations=

My variable Settings.Locations return null instead of empty array. I've tried doing something like this:

public static int[] Locations 
{ 
    get { return new int[] {Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), s => int.Parse(s))}; } 
    set { Config.Write("locations", "ACCOUNT"); } 
}

But that is just not working. I cant convert int[] to int. Do you have any ideas how can I return empty array?

Answer 1

You can do it explicitly like this:

public static int[] Locations
{
    get
    {
        string locations = Config.Read("locations", "ACCOUNT");
        if (locations == null)
        {
            return new int[0];
        }
        return locations
                .Split(',')         // split the locations separated by a comma
                .Select(int.Parse)  // transform each string into the corresponding integer
                .ToArray();         // put the resulting sequence (IEnumerable<int>) into an array of integers
    }
    set
    {
        Config.Write("locations", "ACCOUNT");
    }
}

Answer 2

First of all, you're jamming too much into one line so it makes it really hard to read let alone troubleshoot. What you need is something like this:

public static int[] Locations 
{ 
    get 
    { 
        int[] values = Array.ConvertAll(Config.Read("locations", "ACCOUNT").Split(','), 
            s => int.Parse(s)) ?? new int[] { };
        return values; 
    } 
    set 
    { 
        Config.Write("locations", "ACCOUNT"); 
    } 
}

Notice I have added ?? new int[] { } to the end of the first statement, which is called the null coalescing operator. It will return an empty array if the other array is null.

It's a matter of preference, but the reason I separated the getter into two lines is so I can debug and break before it returns to observe the return value. You could also break on the last bracket instead and observe the return value in the Locals window.