Ruby - Arrays
Given a hash h = {a: 1, b: nil, c: 3, d: nil}
Which Ruby code removes all key-value pairs where the value is nil using compact?
Given a hash h = {a: 1, b: nil, c: 3, d: nil}Which Ruby code removes all key-value pairs where the value is nil using compact?
hard📝 Application Q9 of 15
Step-by-Step Solution
Solution:
Step 1: Understand compact on Hash
Ruby 2.4+ supportscompactandcompact!on Hash to remove pairs with nil values.Step 2: Compare with delete_if
delete_if { |k, v| v.nil? }also removes pairs with nil values by filtering.Step 3: Confirm both methods work
Bothcompact!anddelete_ifmodify the hash in place to remove nil values, so both are correct.Final Answer:
Both B and C -> Option DQuick Check:
compact! and delete_if remove nil pairs = A [OK]
Quick Trick: Use compact! or delete_if to remove nil pairs from hash [OK]
Common Mistakes:
- Thinking compact does not work on Hash
- Confusing compact and compact! on Hash
- Expecting compact to return new hash without assignment
Master "Arrays" in Ruby
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