C# help creating a 1d array from an array of class data

Need some help pulling data out of a class in different orders - think I need reflection but not sure how to set it up.

public class Strike
{
    public float volume { get; private set; }
    public float bid { get; private set; }
    public float ask { get; private set; }
}

In my main thread:

var test = new Strike()
{
    volume = 10,
    bid = 123,
    ask = 125
},
{
    volume = 20,
    bid = 23,
    ask = 27
},
{
    volume = 17,
    bid = 78,
    ask = 92
}

I need to concat the data together but the user can select which order - i.e. volume, bid, ask would be

[10, 20, 17, 123, 23, 78, 125, 27, 92]

or if they want bid, volume ask

[123, 23, 78, 10, 20, 17, 125, 27, 92]

Using linq I can hard code it

var vol = test.Select(s => s.volume);
var bd = test.Select(s => s.bid);
var ak = test.Select(s => s.ask);
var output = vol.Concat(bd).Concat(ak);

How do i make it so that I can call the volume, bid, ask from a different array that I can order how the user would like

I strongly suspect you are not using the correct data structures to begin with. Given the results you want, I'm not sure classes are the best choice.

However, you could do what you want using reflection.

IEnumerable<float> BuildList(Strike[] strikes, params string[] properties)
{
	Type type = typeof(Strike);
	List<PropertyInfo> propertyInfos = new();

    // Build PropertyInfos for each property
	foreach (string property in properties)
	{
		PropertyInfo? info = type.GetProperty(property, BindingFlags.Public | BindingFlags.Instance);
		if (info != null)
			propertyInfos.Add(info);
	}

    // Build resulting list
	for (int i = 0; i < propertyInfos.Count; i++)
	{
		for (int j = 0; j < strikes.Length; j++)
		{
			if (propertyInfos[i].GetValue(strikes[j]) is float f)
				yield return f;
		}
	}
}

You can call the above method like this:

BuildList(test, "bid", "volume", "ask");

It's very simple without reflection:

IEnumerable<float> BuildList(Strike[] strikes, params string[] properties)
{
	var map = new Dictionary<string, Func<Strike, float>>()
	{
		{ "volume", s => s.volume },
		{ "bid", s => s.bid },
		{ "ask", s => s.ask },
	};
	
	return
		from property in properties
		from strike in strikes
		select map[property](strike);
}

If I run this:

var test = new[]
{
	new Strike()
	{
		volume = 10,
		bid = 123,
		ask = 125
	},
	new Strike()
	{
		volume = 20,
		bid = 23,
		ask = 27
	},
	new Strike()
	{
			volume = 17,
		bid = 78,
		ask = 92
	}
};

Console.WriteLine(
	String.Join(
		", ",
		BuildList(test, "volume", "ask", "bid")));

I get 10, 20, 17, 125, 27, 92, 123, 23, 78.

You can Use reflection.first Create List order (strings ) and use foreach to Concat

You just need to enter the desired list (according to the order) in the settings class(Example : ask,bid,volume)

List<string> strings = new List<string>() { "ask", "bid", "volume" };
List<string> list = new List<string>();

foreach (var test in strings)
{
    list.AddRange(tests.Select(x => x.GetType().GetProperty(test).GetValue(x, null).ToString()).ToArray());
}

In the code below, I put the whole code with a test data sample and display the output

var tests = new List<Strike>();
tests.Add(new Strike(){ volume = 10,  bid = 123,  ask = 125 });
tests.Add(new Strike(){ volume = 20, bid = 23,ask = 27});
tests.Add(new Strike(){ volume = 17, bid = 78,ask = 92});

List<string> strings = new List<string>() { "ask", "bid", "volume" };
List<string> list = new List<string>();

foreach (var test in strings)
{
    list.AddRange(tests.Select(x => x.GetType().GetProperty(test).GetValue(x, null).ToString()).ToArray());
}

foreach (var item in list)
{
    Console.WriteLine(item);
}