C#.NET — Trace ref parameter behavior with a struct to determine output. namespace CuriousTabConsoleApplication { struct Sample { public int i; } class MyProgram { static void Main(string[] args) { Sample x = new Sample(); x.i = 10; fun(ref x); Console.Write(x.i + " "); } public static void fun(ref Sample y) { y.i = 20; Console.Write(y.i + " "); } } } What will be printed?

Introduction / Context:
This program demonstrates passing a struct (a value type) by reference using the ref keyword and observing how modifications inside the called method reflect back in the caller. Understanding ref with value types is key because, by default, value types are copied on call and assignment.

Given Data / Assumptions:

• Struct Sample has a single public field i.
• Main initializes x.i = 10, then calls fun(ref x), then prints x.i.
• fun takes ref Sample y, sets y.i = 20, and prints y.i.

Concept / Approach:
With ref, the parameter y is an alias to the caller’s variable x. Any writes to fields of y mutate the same instance that Main later observes. Therefore, setting y.i = 20 will also make x.i equal 20. The order of Write calls determines the sequence printed on the console.

Step-by-Step Solution:

Verification / Alternative check:
If ref were omitted (fun(x)), then fun would receive a copy and x.i would remain 10 in Main, producing "20 10". The ref here is the reason both prints show 20.

Why Other Options Are Wrong:

• A/B/C: Assume either call-by-value semantics or a different print order. They do not match ref behavior.
• E: A definite result exists.

Common Pitfalls:
Confusing ref with out, or assuming structs behave like reference types without ref. With ref/out, the callee can mutate the caller’s variable.

Final Answer:
20 20