Switch with where clauses in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of a where clause in a Swift switch statement?

A where clause adds an extra condition to a case in a switch statement, allowing more precise matching based on additional logic.

beginner

How do you write a switch case with a where clause in Swift?

You write the case pattern followed by <code>where</code> and a condition. For example:<br><pre>case let x where x > 10:</pre>

beginner

Can a switch statement have multiple where clauses in different cases?

Yes, each case can have its own where clause to add specific conditions for that case.

intermediate

What happens if no case with a matching where clause is found in a switch?

If no case matches including its where condition, the default case runs if provided, otherwise the program will not compile because the switch is not exhaustive.

intermediate

Why use where clauses instead of just putting conditions inside the case body?

Using where clauses keeps the switch cases clean and declarative, making it clear which cases apply only under certain conditions before executing code.

What does the where clause do in a Swift switch case?

A Adds an extra condition to the case

B Defines the default case

C Declares a variable

D Ends the switch statement

The where clause adds an extra condition that must be true for the case to match.

Which of these is a valid Swift switch case with a where clause?

A case x > 5 where:

B case where x > 5:

C case let x where x % 2 == 0:

D case x where x > 5:

The correct syntax is case let x where condition:.

If no case matches including its where clause, what happens?

A The switch statement is skipped

B The program crashes

C The first case runs anyway

D The default case runs if present

If no case matches, the default case runs if it exists.

Can multiple cases in a switch have where clauses?

A Only the default case can have a where clause

B Yes, each case can have its own where clause

C No, only one where clause per switch

D Where clauses are not allowed in switch

Each case can have its own where clause to add specific conditions.

Why might you prefer a where clause over an if statement inside a case?

A It makes the case matching clearer and more precise

B It runs faster

C It allows multiple cases to run

D It avoids needing a default case

Where clauses keep the matching logic declarative and clear before executing the case body.

Explain how a where clause works in a Swift switch statement and give an example.

Think about adding extra conditions to cases.

Describe what happens if no switch case matches including its where clause, and how to handle it.

Consider what ensures the switch covers all possibilities.