Question

Is there any difference between these two cases in below program?

static void Main(string[] args)
{
     //Case 1:
     new Program().a();    

     //Case 2:
     Program p = new Program();
     p.a();
}

void a()
{
     // Do some stuff
}

Answer 1

No. You’re creating an object when you call new Program(). p is just a reference to that object, it adds almost nothing at all in terms of memory use or performances.

In terms of style and readability of your code, it is advisable to avoid statements like new Program().a(); – It makes the code harder to debug because you can’t place a brake-point on the statement you want and can’t tell what caused an exception you may have caused.
It is also not too clear what you’re doing – you’d probably need to read that again to fully understand what is created, and what is executed and returned.