public class Test { //Car c = null; // Is this better and is it good to set it to null. public void A() { Car c = new Car(); } public void B() { Car c = new Car(); } public void C() { Car c = new Car(); } } 1) Can I just declare Object 0 globally at the top and use it in each method instead of creating a new one each time (Is this what I am actually doing?)
2) Is it a good idea to initially set the object to null?
FxCop states that you should avoid unnecessary initialising code, because it generates unnecessary IL, which affects performance. (Although I think that the performance hit is very minimal). Sometimes, I also explicitly initialize variables, just to make my code more clear.
To answer your first question: it's all a matter of what you're trying / wanting to do ...
This is a duplicate question and has been asked many times on SO. The answer is, "it's a matter of style". Some prefer a style that indicates understanding of the fact that the compiler will initialize to null. Others prefer a style that makes it unnecessary to understand that the compiler will initialize to null.
1) Can I just declare Object 0 globally at the top and use it in each method instead of creating a new one each time (Is this what I am actually doing?)
Apart from the invalid name for an object (compare 0 and O), yes, you can. Redeclaring creates another variable with local scope, it does not modify the private member of the class.
2) Is it a good idea to initially set the object to null?
It’s unnecessary since this is done automatically when an object of your class is created.
cclass member object.