Why do we use the "new" keyword when initialising a Vector3, but not an integer?

Question

Why is it then if I were to initialise a string or an integer I could simply do this:

int number = 1;
string word = "word";

But if I want to initialise a Vector3 then I have to do:

Vector3 coordinate = new Vector3(1f,1f,1f);

The context to this is that I was creating a pretty large array and had to write out new Vector3... every time and it got pretty tedious:

Vector3[,] coordsList = new Vector3[11, 11]
{
    {new Vector3(-1.32f,1.32f), new Vector3(-1.08f,1.32f), new Vector3(-0.84f,1.32f), new Vector3(-0.6f,1.32f), new Vector3(-0.36f,1.32f), new Vector3(-0.12f,1.32f), new Vector3(0.12f,1.32f), new Vector3(0.36f,1.32f), new Vector3(0.6f,1.32f), new Vector3(0.84f,1.32f), new Vector3(1.08f,1.32f) },
    {new Vector3(-1.32f,1.08f), new Vector3(-1.08f,1.08f), new Vector3(-0.84f,1.08f), new Vector3(-0.6f,1.08f), new Vector3(-0.36f,1.08f), new Vector3(-0.12f,1.08f), new Vector3(0.12f,1.08f), new Vector3(0.36f,1.08f), new Vector3(0.6f,1.08f), new Vector3(0.84f,1.08f), new Vector3(1.08f,1.08f) },
    {new Vector3(-1.32f,0.84f), new Vector3(-1.08f,0.84f), new Vector3(-0.84f,0.84f), new Vector3(-0.6f,0.84f), new Vector3(-0.36f,0.84f), new Vector3(-0.12f,0.84f), new Vector3(0.12f,0.84f), new Vector3(0.36f,1.32f), new Vector3(0.6f,0.84f), new Vector3(0.84f,0.84f), new Vector3(1.08f,0.84f) },
    {new Vector3(-1.32f,0.60f), new Vector3(-1.08f,0.60f), new Vector3(-0.84f,0.60f), new Vector3(-0.6f,0.60f), new Vector3(-0.36f,0.60f), new Vector3(-0.12f,0.60f), new Vector3(0.12f,0.60f), new Vector3(0.36f,0.60f), new Vector3(0.6f,0.60f), new Vector3(0.84f,0.60f), new Vector3(1.08f,0.60f) },
    {new Vector3(-1.32f,0.36f), new Vector3(-1.08f,0.36f), new Vector3(-0.84f,0.36f), new Vector3(-0.6f,0.36f), new Vector3(-0.36f,0.36f), new Vector3(-0.12f,0.36f), new Vector3(0.12f,0.36f), new Vector3(0.36f,0.36f), new Vector3(0.6f,0.36f), new Vector3(0.84f,0.36f), new Vector3(1.08f,0.36f) },
    {new Vector3(-1.32f,0.12f), new Vector3(-1.08f,0.12f), new Vector3(-0.84f,0.12f), new Vector3(-0.6f,0.12f), new Vector3(-0.36f,0.12f), new Vector3(-0.12f,0.12f), new Vector3(0.12f,0.12f), new Vector3(0.36f,0.12f), new Vector3(0.6f,0.12f), new Vector3(0.84f,0.12f), new Vector3(1.08f,0.12f) },
    {new Vector3(-1.32f,-0.12f), new Vector3(-1.08f,-0.12f), new Vector3(-0.84f,-0.12f), new Vector3(-0.6f,-0.12f), new Vector3(-0.36f,-0.12f), new Vector3(-0.12f,-0.12f), new Vector3(0.12f,1.32f), new Vector3(0.36f,-0.12f), new Vector3(0.6f,-0.12f), new Vector3(0.84f,-0.12f), new Vector3(1.08f,-0.12f) },
    {new Vector3(-1.32f,-0.36f), new Vector3(-1.08f,-0.36f), new Vector3(-0.84f,-0.36f), new Vector3(-0.6f,-0.36f), new Vector3(-0.36f,-0.36f), new Vector3(-0.12f,-0.36f), new Vector3(0.12f,-0.36f), new Vector3(0.36f,-0.36f), new Vector3(0.6f,-0.36f), new Vector3(0.84f,-0.36f), new Vector3(1.08f,-0.36f) },
    {new Vector3(-1.32f,-0.6f), new Vector3(-1.08f,-0.6f), new Vector3(-0.84f,-0.6f), new Vector3(-0.6f,-0.6f), new Vector3(-0.36f,-0.6f), new Vector3(-0.12f,-0.6f), new Vector3(0.12f,-0.6f), new Vector3(0.36f,-0.6f), new Vector3(0.6f,-0.6f), new Vector3(0.84f,-0.6f), new Vector3(1.08f,-0.6f) },
    {new Vector3(-1.32f,-0.84f), new Vector3(-1.08f,-0.84f), new Vector3(-0.84f,-0.84f), new Vector3(-0.6f,-0.84f), new Vector3(-0.36f,-0.84f), new Vector3(-0.12f,-0.84f), new Vector3(0.12f,-0.84f), new Vector3(0.36f,-0.84f), new Vector3(0.6f,-0.84f), new Vector3(0.84f,-0.84f), new Vector3(1.08f,-0.84f) },
    {new Vector3(-1.32f,-1.08f), new Vector3(-1.08f,-1.08f), new Vector3(-0.84f,-1.08f), new Vector3(-0.6f,-1.08f), new Vector3(-0.36f,-1.08f), new Vector3(-0.12f,-1.08f), new Vector3(0.12f,-1.08f), new Vector3(0.36f,-1.08f), new Vector3(0.6f,-1.08f), new Vector3(0.84f,-1.08f), new Vector3(1.08f,-1.08f) },
};

But yet it would have been considerably easier had it been an array of integers? What is it about a Vector3 that requires this new keyword that an integer or a string does not.

Answer 1

Vector3[][] list = new (float x, float y)[][]
{
    new[] { (1.5f, 3.4f), (1.5f, 6.8f) },
    new[] { (1.5f, 3.4f), (1.5f, 6.8f) },
    new[] { (1.5f, 3.4f), (1.5f, 6.8f) },
    new[] { (1.5f, 3.4f), (1.5f, 6.8f) },
}.Select(r => r.Select(v => new Vector3(v.x, v.y)).ToArray()).ToArray();

You could use Value Tuples (now supported in the latest version of Unity 2018.3) to construct your data in a readable and less tedious way - then you can use Select to transform these into Vector3s.

I think most of the comments adequately cover your questions about the hows and whys of the new keyword here.

Answer 2

The reason that the Vector3 requires the new keyword is that a Vector3 is a struct built into Unity, so every time you use the new keyword, you are making a new instance of a Vector3 struct, whereas with a string or an int, these basic data types are from C#.

Hope this helps explain the difference!