Using LINQ to flatten a data structure v Old-Skool C# code

gistfile1.cs

private static void FlattenData()
{
    var dictionary = new Dictionary<string, string[]> {
        { "Foo", new [] { "foo-1", "foo-2" }},
        { "Bar", new [] { "bar-1", "bar-2" }}
    };

    IEnumerable<string> flattenedData;

    // Using LINQ
    flattenedData = dictionary.Values.SelectMany(d => d).ToArray();

    // Old-school way
    foreach (var key in dictionary.Keys)
    {
        var dataSubset = dictionary[key];
        flattenedData = flattenedData.Concat(dataSubset);
    }
            
    // Old-school way (compact)
    foreach (var key in dictionary.Keys)
        flattenedData = flattenedData.Concat(dictionary[key]);
}