Which of the following is the correct syntax to create a Ruby hash with a default value of an empty array for missing keys?

easy📝 Syntax Q12 of 15

Ruby - Hashes

Ah = Hash.new { |key| [] }

Bh = Hash.new { [] }

Ch = Hash.new([])

Dh = Hash.new { |hash, key| hash[key] = [] }

Step-by-Step Solution

Solution:

Step 1: Understand default block usage
Using a block with Hash.new allows dynamic default values. To assign a new array to each missing key, the block must assign it to the hash.
Step 2: Identify correct block syntax
The block receives hash and key parameters and assigns [] to hash[key]. This ensures each missing key gets its own array.
Final Answer:
h = Hash.new { |hash, key| hash[key] = [] } -> Option D
Quick Check:
Block assigns new array to missing keys [OK]

Quick Trick: Use block with two params to assign default arrays [OK]

Common Mistakes:

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