You want to create a Proc that returns the square of a number and then call it for numbers 1 to 3, collecting results in an array. Which code correctly does this?

hard📝 Application Q8 of 15

Ruby - Blocks, Procs, and Lambdas

Asquare = proc { |n| n * n } results = (1..3).map { |x| square.call(x) } puts results.inspect

Bsquare = proc { |n| n ** 2 } results = (1..3).each { |x| square.call(x) } puts results.inspect

Csquare = proc { |n| n * n } results = (1..3).map { |x| square(x) } puts results

Dsquare = proc { |n| n * n } results = (1..3).map { |x| square.call } puts results.inspect

Step-by-Step Solution

Solution:

Step 1: Check Proc definition
A valid Proc for squaring uses proc { |n| n * n } or equivalent n ** 2.
Step 2: Verify collection method and call syntax
Correct code uses (1..3).map { |x| square.call(x) } to collect [1, 4, 9]; each returns original range, missing .call or arg causes error.
Step 3: Confirm output
puts results.inspect prints [1, 4, 9].
Final Answer:
square = proc { |n| n * n } results = (1..3).map { |x| square.call(x) } puts results.inspect -> Option A
Quick Check:
Outputs [1, 4, 9] [OK]

Quick Trick: Use map with .call to collect Proc results in array [OK]

Common Mistakes:

Using each instead of map for collecting results
Calling Proc without arguments
Trying to call Proc like a method without .call

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More Ruby Quizzes

You want to create a Proc that returns the square of a number and then call it for numbers 1 to 3, collecting results in an array. Which code correctly does this?

Step 1: Check Proc definition

Step 2: Verify collection method and call syntax

Step 3: Confirm output

Final Answer:

Quick Check:

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