C#.NET — Implementing a bounds-checked indexed property (indexer) for a 5-element scores array. Goal: The indexer should print "Invalid Index" when the user accesses beyond the last valid index.

Question

Solve this multiple-choice question and choose the correct option.

Accepted Answer

Introduction / Context:Indexers in C#.NET allow array-like access to class or struct instances. Here, the Student indexer should both read and write scores while warning when the index exceeds the allowed range. Given Data / Assumptions: scores is an int[5]. Valid indices are 0..4. Requirement: print "Invalid Index" when out of bounds. We accept a simple check (index < 5); in production, include index >= 0 as well. Concept / Approach:A well-formed indexer includes both get and set accessors when read-write access is needed. Each accessor should validate the index and either proceed or report an error state. Step-by-Step Solution: Choose an indexer with both get and set accessors. In get: return scores[index] if valid; otherwise print a message and return a safe default (e.g., 0). In set: assign scores[index] if valid; otherwise print a message. Verification / Alternative check:Testing with index = 4 works; index = 5 prints "Invalid Index". Adding index < 0 checks further hardens the code. Why Other Options Are Wrong: A: Write-only; lacks a getter. C: Read-only; lacks a setter. D: Accessor bodies are swapped/incorrect and will not compile. E: Incorrect because a correct implementation exists (option B). Common Pitfalls:Forgetting the lower-bound check or mixing up get/set logic bodies. Final Answer:Option B (read-write indexer with bounds check) is correct.

C#.NET — Implementing a bounds-checked indexed property (indexer) for a 5-element scores array. Goal: The indexer should print "Invalid Index" when the user accesses beyond the last valid index.

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