array size change in C#

ArraySizeChange.cs

void Main()
{
	// resize
	var a = new[] { 1, 2, 3 };
	Array.Resize(ref a, a.Length + 1); // 突然のref
	a[a.Length - 1] = 4;
	a.Dump();

	// copy
	var b = new[] { 1, 2, 3 };
	var c = new int[4]; // 型明示が必要....
	Array.Copy(b, c, b.Length);
	c[b.Length] = 4;
	c.Dump();

	// concat
	var d = new[] { 1, 2, 3 };
	var e = d.Concat(new[] {4}).ToArray(); // LINQ....
	e.Dump();
}