[Solved] What is the output of the following code?object obj = "hello"; string s = obj as string; Console.WriteLine(s != null ? s.ToUpper() : "null"); | C Sharp (C#)

C Sharp (C#) - Polymorphism and Abstract Classes

What is the output of the following code?

object obj = "hello";
string s = obj as string;
Console.WriteLine(s != null ? s.ToUpper() : "null");

AHELLO

Bnull

Chello

DRuntime error

Step-by-Step Solution

Solution:

Step 1: Analyze the as cast
The object obj holds a string "hello". Using as string casts it successfully, so s is "hello".
Step 2: Evaluate the conditional output
Since s is not null, s.ToUpper() is called, producing "HELLO".
Final Answer:
HELLO -> Option A
Quick Check:
as cast success means uppercase output [OK]

Quick Trick: If as cast succeeds, use the object; else null [OK]

Common Mistakes:

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