Why is it possible to instantiate a struct without the new keyword?

Question

Why are we not forced to instantiate a struct, like when using a class?

Answer 1

Because a struct is a value-type. When you declare a variable of it, the instance is immediateley there.

A constructor (the new operator) is therefore optional for a struct.

Consider

struct V { public int x; }
class  R { public int y = 0; }

void F() 
{
   V a;   // a is an instance of V, a.x is unassigned  
   R b;   // b is a reference to an R

   a.x = 1; // OK, the instance exists
 //b.y = 2; // error, there is no instance yet

   a = new V();  // overwrites the memory of 'a'. a.x == 0
   b = new R();  // allocates new memory on the Heap

   b.y = 2; // now this is OK, b points to an instance
}