Computed properties in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a computed property in C#?

A computed property is a property that calculates its value dynamically using code in its getter, instead of storing a value directly.

beginner

How do you define a computed property in C#?

You define a computed property by providing only a getter with code that returns a calculated value, without a backing field.

beginner

Example: What does this computed property do?

public int DoubleAge => Age * 2;

This property returns twice the value of the Age property whenever accessed. It does not store a value but computes it on the fly.

intermediate

Can computed properties have setters in C#?

No, computed properties usually only have getters because their value is calculated. If you add a setter, it must store a value somewhere.

intermediate

Why use computed properties instead of fields?

Computed properties keep data consistent by calculating values on demand, avoiding errors from storing outdated values.

What keyword is used to define a computed property with a single expression in C#?

A var

B get

C set

D =>

The '=>' symbol defines an expression-bodied member, often used for computed properties.

Which of these is true about computed properties in C#?

A They store values in private fields.

B They calculate values when accessed.

C They must have both get and set.

D They cannot use other properties.

Computed properties calculate and return values dynamically when accessed.

What happens if you try to assign a value to a computed property with only a getter?

A It compiles and stores the value.

B It throws a runtime error.

C It causes a compile-time error.

D It ignores the assignment.

Computed properties with only getters cannot be assigned to; this causes a compile-time error.

Which is a benefit of using computed properties?

A They reduce memory by not storing redundant data.

B They make code slower.

C They require manual updates.

D They prevent any calculations.

Computed properties save memory by calculating values on demand instead of storing them.

How do you write a computed property that returns the length of a string property 'Name'?

A public int NameLength => Name.Length;

B public int NameLength { get; set; }

C public int NameLength = Name.Length;

D public int NameLength() { return Name.Length; }

Option A uses an expression-bodied computed property to return the length of 'Name'.

Explain what a computed property is and why it is useful in C#.

Think about properties that calculate values instead of storing them.

Write a simple computed property in C# that returns the full name by combining first and last names.

Use string interpolation or concatenation inside the getter.