Solution:Step 1: Identify the thrown exception and its propertyThe code throws ArgumentNullException with ParamName set to "param".Step 2: Check the when clause condition in the first catchThe first catch has a when clause checking if ex.ParamName == "param", which is true, so this catch runs.Step 3

[Solved] Consider this code:try { throw new ArgumentNullException("param"); } catch (ArgumentNullException ex) when (ex.ParamName == "param") { Console.... }What will be printed and why? | C Sharp (C#)

C Sharp (C#) - Exception Handling

Consider this code:

try {
    throw new ArgumentNullException("param");
} catch (ArgumentNullException ex) when (ex.ParamName == "param") {
    Console.WriteLine("Parameter error");
} catch (ArgumentNullException ex) {
    Console.WriteLine("Other argument null error");
}

What will be printed and why?

AParameter error, because the when condition matches the ParamName.

BOther argument null error, because when clause is ignored.

CNo output, because exception is not caught.

DRuntime error due to duplicate catch blocks.

Step-by-Step Solution

Solution:

Step 1: Identify the thrown exception and its property
The code throws ArgumentNullException with ParamName set to "param".
Step 2: Check the when clause condition in the first catch
The first catch has a when clause checking if ex.ParamName == "param", which is true, so this catch runs.
Step 3: Understand catch block selection
The second catch is ignored because the first matching catch with true when condition handles the exception.
Final Answer:
Parameter error, because the when condition matches the ParamName. -> Option A
Quick Check:
when true catches first matching block [OK]

Quick Trick: when filters catch; first true condition wins [OK]

Common Mistakes:

MISTAKES

Ignoring when condition and picking second catch
Thinking duplicate catch causes error
Assuming exception is uncaught

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More C Sharp (C#) Quizzes

Consider this code:

Step 1: Identify the thrown exception and its property

Step 2: Check the when clause condition in the first catch

Step 3: Understand catch block selection

Final Answer:

Quick Check:

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