Object instantiation with new in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the new keyword do in C#?

The <code>new</code> keyword creates a new instance (object) of a class in memory, allowing you to use that object in your program.

beginner

How do you create a new object of a class named <code>Car</code>?

You write: <br>Car myCar = new Car(); <br>This creates a new Car object and stores it in the variable myCar.

beginner

Why do you need to use new to create objects?

Using new tells the computer to allocate memory for the object and run its constructor to set it up properly.

intermediate

What happens if you declare a variable of a class type without using <code>new</code>?

The variable will be null (empty) and does not point to any object. Trying to use it will cause a NullReferenceException at runtime.

beginner

Can you instantiate an object without parentheses after the class name? For example: <code>new Car;</code>

No, in C# you must include parentheses even if the constructor has no parameters: new Car(); is correct.

What does new do in C#?

A Declares a variable

B Deletes an object

C Creates a new object instance

D Calls a method

new creates a new object instance in memory.

Which is the correct way to instantiate a class named Dog?

A Dog d = Dog();

B Dog d = new Dog();

C Dog d = new Dog;

D Dog d = new;

You must use new Dog(); with parentheses to create a new object.

What happens if you declare Car myCar; without new?

A myCar is null and unusable

B myCar is a new object

C myCar is a number

D myCar is a string

Without new, the variable is null and does not reference an object.

Why do you need parentheses after the class name when using new?

A Parentheses are optional

B To declare a variable

C To assign a value

D To call the constructor method

Parentheses call the constructor to initialize the new object.

Which statement is true about object instantiation?

A The <code>new</code> keyword allocates memory for the object

B You can create an object without <code>new</code>

C Objects are created automatically without code

D Variables hold objects directly without references

new allocates memory and creates the object instance.

Explain in your own words what happens when you use new to create an object in C#.

Think about what the computer does behind the scenes when you write <code>new ClassName()</code>.

Describe the difference between declaring a variable of a class type and instantiating an object with new.

Consider what the variable holds before and after using <code>new</code>.