[Solved] What is the output of the following Ruby code?h = Hash.new { |hash, key| hash[key] = [] } h[:a] — Ans: {:a=>[1], :b=>[2]} | Ruby

Ruby - Hashes

What is the output of the following Ruby code?

h = Hash.new { |hash, key| hash[key] = [] }
h[:a] << 1
h[:b] << 2
p h

A{:a=>[1], :b=>[2], :c=>[]}

B{:a=>[1], :b=>[2], nil=>[]}

C{:a=>[1], :b=>[2]}

D{}

Step-by-Step Solution

Solution:

Step 1: Understand default block behavior
The hash is created with a block that assigns an empty array to missing keys when accessed.
Step 2: Modify arrays for keys :a and :b
Appending 1 to h[:a] creates :a => [1]. Similarly, appending 2 to h[:b] creates :b => [2].
Step 3: Print the hash
Only keys :a and :b have values. No other keys exist.
Final Answer:
{:a=>[1], :b=>[2]} -> Option C
Quick Check:
Default arrays assigned and modified correctly [OK]

Quick Trick: Default block assigns new array per missing key [OK]

Common Mistakes:

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