C#.NET — Identify valid ways to create an object of class Sample. Consider the following possibilities: Sample s = new Sample(); Sample s; Sample s; s = new Sample(); s = new Sample(); Which options correctly create an object?
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A1, 3
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B2, 4
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C1, 2, 3
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D1, 4
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ENone of these
Answer
Correct Answer: 1, 3
Explanation
Introduction / Context:Creating objects in C#.NET requires instantiation with new. This problem distinguishes between merely declaring a reference and actually creating an instance.
Given Data / Assumptions:
- Sample is a reference type (class).
- We compare declaration vs instantiation.
Concept / Approach:A declaration like Sample s; creates only a reference variable (initialized to null if it is a field, uninitialized if local). An object is created only when new Sample() is executed. You can create and assign in one step or two steps.
Step-by-Step Solution:
(1) Valid: both declares and instantiates.(2) Only declares a reference; no object created.(3) Valid: declare first, then instantiate and assign.(4) Invalid alone: s must be declared before assignment.Verification / Alternative check:Attempt to access s after (2) without instantiation raises NullReferenceException if used; after (1) or (3) you have a real object.
Why Other Options Are Wrong:They include cases that do not create an object or that use an undeclared identifier.
Common Pitfalls:Assuming declaration implies construction; in C# these are distinct steps (though they can be combined).
Final Answer:1, 3