Switch expression (modern C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a switch expression in modern C#?

A switch expression is a concise way to select a value based on a pattern match, introduced in C# 8.0. It returns a value directly instead of using statements.

beginner

How does a switch expression differ from a traditional switch statement?

A switch expression returns a value and is used inline, while a switch statement executes code blocks and does not return a value directly.

beginner

What symbol is used to separate the input and the result in a switch expression case?

The '=>' symbol is used to separate the input pattern from the result expression in each case of a switch expression.

intermediate

Can switch expressions in C# use pattern matching?

Yes, switch expressions support pattern matching, allowing you to match types, values, and conditions directly in the cases.

intermediate

What happens if no case matches in a switch expression and no default case is provided?

If no case matches and there is no default case (using '_'), the switch expression throws a System.Runtime.CompilerServices.SwitchExpressionException at runtime.

Which symbol is used to separate the pattern and result in a C# switch expression?

A =>

B :

C ->

D =

The '=>' symbol separates the input pattern from the output expression in each case of a switch expression.

What does a switch expression return?

A An exception always

B A value based on the matched case

C A boolean indicating if a case matched

D Nothing, it only executes code blocks

Switch expressions return a value directly based on the matched case.

Which C# version introduced switch expressions?

A C# 7.0

B C# 6.0

C C# 9.0

D C# 8.0

Switch expressions were introduced in C# 8.0.

What keyword is used as a default case in switch expressions?

A _

B default

C else

D case

The underscore '_' is used as a discard pattern to represent the default case in switch expressions.

Can switch expressions use pattern matching with types?

A Only with strings

B No

C Yes

D Only with integers

Switch expressions support pattern matching with types, values, and conditions.

Explain how a switch expression works in modern C# and give a simple example.

Think about how you choose an option and get a result in one line.

Describe the difference between a switch statement and a switch expression in C#.

One is like a list of instructions, the other is like a calculator.