Each for iteration in Ruby - Step-by-Step Execution

Concept Flow - Each for iteration

Start with collection

↓

Pick next element

↓

Run block with element

↓

More elements?

No→End iteration

↩Back to Pick next element

The 'each' method takes each element from a collection one by one and runs the given block of code with it until all elements are processed.

Execution Sample

Ruby

numbers = [1, 2, 3]
numbers.each do |num|
  puts num * 2
end

This code goes through each number in the list and prints double its value.

Execution Table

Iteration	num value	Action	Output
1	1	Run block with num=1	2
2	2	Run block with num=2	4
3	3	Run block with num=3	6
-	-	No more elements, iteration ends	-

💡 All elements processed, 'each' loop ends

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
num	nil	1	2	3	nil

Key Moments - 2 Insights

Why does 'num' change each iteration?

'num' takes the value of the current element from the collection each time the block runs, as shown in execution_table rows 1 to 3.

What happens after the last element is processed?

The loop stops because there are no more elements, as shown in the last row of execution_table where iteration ends.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'num' during iteration 2?

A 1

B 2

C 3

D nil

💡 Hint

Check the 'num value' column in the second row of execution_table.

At which iteration does the loop stop running the block?

A After iteration 1

B After iteration 2

C After iteration 3

D It never stops

💡 Hint

Look at the exit note and the last row in execution_table.

If the array was empty, what would happen to the 'num' variable?

A It would never be set and block never runs

B It would be set to nil and block runs once

C It would be set to 0

D It would cause an error

💡 Hint

Refer to variable_tracker and understand that 'num' changes only when block runs.

Concept Snapshot

Ruby 'each' method:
- Goes through each element in a collection
- Runs the block with current element as variable
- Stops after last element
- Variable inside block changes each iteration
- No output unless block prints or returns

Full Transcript

The Ruby 'each' method takes a collection like an array and runs a block of code for each element. In the example, numbers 1, 2, and 3 are processed one by one. The variable 'num' holds the current element's value during each iteration. The block prints double the number. After all elements are done, the loop ends. If the array is empty, the block never runs and 'num' stays nil.