Question

I am using the first way and my new company is using the second way.

double x = 1.99; 

double y = 9.02D; 

Which one is correct and why?

If both is correct, then how to use this is in different scenarios?

Answer 1

From msdn:

By default, a real numeric literal on
the right-hand side of the assignment
operator is treated as double.
However, if you want an integer number
to be treated as double, use the
suffix d or D, for example: Copy

double x = 3D;

So there is no difference between double x = 1.99; and double y = 9.02D;