Given the array [1, 2, 3, 4], which block syntax correctly filters even numbers and returns them as a new array?

hard📝 Application Q15 of 15

Ruby - Blocks, Procs, and Lambdas

Given the array [1, 2, 3, 4], which block syntax correctly filters even numbers and returns them as a new array?

A[1, 2, 3, 4].select { |n| n.even? }

B[1, 2, 3, 4].select do |n| n.even?

C[1, 2, 3, 4].select { n.even? }

D[1, 2, 3, 4].select do n.even? end

Step-by-Step Solution

Solution:

Step 1: Understand the select method and block parameters
select filters elements for which the block returns true. The block must receive each element as a parameter.
Step 2: Check syntax correctness
[1, 2, 3, 4].select { |n| n.even? } correctly uses curly braces with block parameter |n| and calls n.even?. [1, 2, 3, 4].select do |n| n.even? has a syntax error (missing end). [1, 2, 3, 4].select { n.even? } misses block parameters. [1, 2, 3, 4].select do n.even? end misses pipes around parameter.
Final Answer:
[1, 2, 3, 4].select { |n| n.even? } -> Option A
Quick Check:
Curly braces with pipes for single-line filter [OK]

Quick Trick: Use { |var| condition } for concise filtering blocks [OK]

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