Duplicate when clauses

Explanation

The case statement is used to evaluate the size of array a. In this case, a.size equals 2.

The first when clause checks if a.size is 2. Since it is, 1 is appended to the res array.

The second when clause also checks if a.size is 2.

However, in Ruby, case statements execute only the first matching when clause and then exit the case block. Therefore, this second clause is never executed.

So the res array ends up with just [1], because the first when clause matched, and the second one was ignored.

Key Takeaways

Single Execution of when Clauses

In a case statement, only the first matching when clause is executed.

Subsequent matching when clauses are not evaluated, which is why res contains only [1] and not [2].

Order Matters

The order of when clauses is crucial. If the order were reversed, res would contain [2] instead.