Instance fields and state in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an instance field in C#?

An instance field is a variable declared inside a class but outside any method. Each object (instance) of the class has its own copy of this variable, which holds the object's state.

beginner

How does an instance field differ from a static field?

An instance field belongs to each object separately, so each object has its own value. A static field belongs to the class itself and is shared by all objects of that class.

beginner

Why do instance fields represent the state of an object?

Because instance fields store data unique to each object, they describe the current condition or characteristics of that object, which is called its state.

beginner

Consider this code snippet:<br><pre>class Car { public string color; }</pre><br>What does the 'color' field represent?

The 'color' field is an instance field that stores the color of each Car object. Each Car can have a different color stored in its own 'color' field.

beginner

How do you access an instance field in C#?

You access an instance field through an object of the class using the dot (.) operator. For example: <code>myObject.fieldName</code>.

What does an instance field store in C#?

A Data unique to each object

B Data shared by all objects

C Only constant values

D Temporary method variables

Instance fields hold data unique to each object, representing its state.

How do you declare an instance field in a class?

A Inside a method

B Using the static keyword

C Outside methods but inside the class

D Only in interfaces

Instance fields are declared inside the class but outside any method.

Which keyword makes a field shared by all objects of a class?

A shared

B static

C instance

D public

The 'static' keyword makes a field shared by all instances of the class.

If you create two objects of a class, how many copies of an instance field exist?

A Two copies, one per object

B None

C One copy shared by both

D Depends on the field type

Each object has its own copy of instance fields.

How do you access an instance field named 'age' of an object 'person'?

A age.person()

B age.person

C person->age

D person.age

Use the dot operator: objectName.fieldName, so person.age.

Explain what instance fields are and how they relate to an object's state.

Think about how each object remembers its own information.

Describe the difference between instance fields and static fields in C#.

Consider who owns the data: the object or the class.