CODEWITHSUNDEEP
c#list
GIStack
GIStack

Reputation: 113

subtle differences in creating new list?

I am to c# and have been putting programs together through modification of existing code in visual studio. I am looking for some guidance to understand the difference between two ways of creating a list. both compile:

List <int> myList;

//versus

List <int> myList = new List <int>();

Upvotes: 1

Views: 120

Answers (5)

Garrett Vlieger
Garrett Vlieger

Reputation: 9494

The first one List myList; simply declares the variable, but the value is unassigned. The second one actually creates a new List object with no entries in it.

You should use the second option in most cases.

Upvotes: 3

FishBasketGordo
FishBasketGordo

Reputation: 23132

The first line doesn't create a List<int> object. It only declares a variable named myList that's of the type List<int>. If you tried to do anything with that variable as is, the compiler would complain, because it's uninitialized.

The second line declares the variable and initializes it to a value: a new List<int> object.

Upvotes: 0

Chuck Savage
Chuck Savage

Reputation: 11945

List <int> myList;

is the same as writing

List <int> myList = null; // aka it is not a list yet

Upvotes: 0

mfeingold
mfeingold

Reputation: 7154

The first line just creates a variable to hold a reference to a list.

The second one initializes the refrence with an empty list.

An attempt to call any method/access property on a reference without initializing it will end up in a null pointer exception

Upvotes: 1

John Saunders
John Saunders

Reputation: 161773

It's not subtle. One creates a list and one does not.

The first one simply declares a reference to a list. You would have to create the list later, before using it.

The second one declares a reference to a list and creates a list and sets the reference to refer to the new list, all at the same time.

Upvotes: 8

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