For loop (rarely used in Ruby) - Step-by-Step Execution

Concept Flow - For loop (rarely used in Ruby)

Initialize loop variable

↓

Check condition: variable in range?

No→EXIT

Yes↓

Execute loop body

↓

Update loop variable to next value

↩Back to Check

The for loop starts by setting a variable, checks if it is within a range, runs the loop body if yes, then moves to the next value until the condition fails.

Execution Sample

Ruby

for i in 1..3
  puts i
end

This code prints numbers 1 to 3 using a for loop.

Execution Table

Iteration	i value	Condition (i in 1..3)	Action	Output
1	1	true	Print i	1
2	2	true	Print i	2
3	3	true	Print i	3
4	4	false	Exit loop

💡 Next value 4 is outside 1..3, so condition is false and loop stops

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
i	undefined	1	2	3	4

Key Moments - 2 Insights

Why does the loop stop after printing 3?

Because the condition checks if i is in 1..3. After i=3, next would be 4 (see execution_table row 4), it is outside the range, so the loop ends.

Is the loop variable i accessible after the loop ends?

Yes, in Ruby the loop variable i keeps its last value after the loop (which is 4 here, see variable_tracker final).

Visual Quiz - 3 Questions

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

A 1

B 2

C 3

D 4

💡 Hint

Check the 'i value' column in execution_table row for iteration 2.

At which iteration does the loop condition become false?

A Iteration 4

B Iteration 1

C Iteration 3

D Iteration 2

💡 Hint

Look at the 'Condition' column in execution_table where it changes to false.

If the range changed to 1..2, how many times would the loop run?

A 3 times

B 1 time

C 2 times

D 4 times

💡 Hint

Refer to how the range controls iterations in execution_table and variable_tracker.

Concept Snapshot

for loop syntax:
for variable in range
  # code
end

Runs code for each value in range.
Stops when values end.
Loop variable keeps last value after loop.

Full Transcript

This visual trace shows how a for loop works in Ruby. The loop variable i starts at 1 and goes up to 3. Each iteration prints i. After printing 3, next would be 4 but condition fails and the loop stops. The variable i keeps its last value after the loop ends. This example helps beginners see each step clearly.