Which of the following expressions correctly checks if obj is an instance of class String or its subclass?

easy📝 Conceptual Q2 of 15

Ruby - Inheritance

Which of the following expressions correctly checks if obj is an instance of class String or its subclass?

Aobj.is_a?(String)

Bobj.kind_of?(Integer)

Cobj.instance_of?(String)

Dobj.is_a?(Array)

Step-by-Step Solution

Solution:

Step 1: Identify the correct method and class
To check if obj is a String or subclass, use is_a? with String.
Step 2: Verify options
Only obj.is_a?(String) uses is_a? with String. Others check wrong classes or use instance_of? which does not check subclasses.
Final Answer:
obj.is_a?(String) -> Option A
Quick Check:
Check subclass with is_a? = obj.is_a?(String) [OK]

Quick Trick: Use is_a? to check class or subclass membership [OK]

Common Mistakes:

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