Using list arrays - Best practices

Question

I have a c# newbie question. What is consider good practice out of the two below too? ...and is list slower or faster than the array?

        //Method 1
        int[] i_array = { 2, 0, 110, 53455, 2223 };

        if (someBolean)
        {
            Array.Resize(ref i_array, i_array.Length + 1);
            i_array[i_array.Length - 1] = someIntValue;
        }

        //Method 2
        var i_list = new List<int>();
        i_list.AddRange(new int[] { 2, 0, 110, 53455, 2223 });

        if (someBolean)
            i_list.Add(someIntValue);

Answer 1

Use lists when you need a collection that can grow or shrink.

Use arrays if you know the length and don't want to change it.

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You can use collection initializers to initialize a list, so you get similar syntax to initializing an array:

var list = new List<int> { 2, 0, 110, 53455, 2223 };

if (someBoolean)
{
    list.Add(someIntValue);
}

Answer 2

The later is considered the best practice for variable size collections.

Depending on which type of collection you're using, the Framework class will do something internally similar to what you're doing in your first example (except instead of resizing by one element, it increments by a larger size so you have extra buffer space to keep adding elements).

In general, though, you don't want to re-invent the wheel. The framework provides a ton of collection classes that are variable size. Use them instead of writing your own.