For loop with ranges in Kotlin - Step-by-Step Execution

Concept Flow - For loop with ranges

Start

↓

Set range start..end

↓

For each value in range

↓

Execute loop body

↓

Next value in range?

No→Exit loop

↩Back to Execute loop body

The loop starts by defining a range, then runs the loop body for each value in that range, moving to the next value until the end.

Execution Sample

Kotlin

for (i in 1..3) {
    println(i)
}

Prints numbers 1, 2, and 3 using a for loop over a range.

Execution Table

Iteration	i	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 would be 4, which is outside the range 1..3, so the loop stops

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
i	-	1	2	3	3

Key Moments - 2 Insights

Why does the loop stop before i becomes 4?

Because the range is from 1 to 3, and 4 is outside this range, so the condition i in 1..3 becomes false before assigning i=4 (see execution_table row 4).

Is the last value in the range included in the loop?

Yes, the range 1..3 includes 3, so the loop runs when i is 3 (see execution_table row 3).

Visual Quiz - 3 Questions

Look at the execution table, what is the value of i during the second iteration?

A 2

B 3

C 1

D 4

💡 Hint

Check the 'i' column in the execution_table at iteration 2.

At which iteration does the loop condition become false?

A 3

B 4

C 1

D 2

💡 Hint

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

If the range was changed to 1..4, how many times would the loop run?

A 3 times

B 5 times

C 4 times

D 2 times

💡 Hint

The loop runs once for each number in the range, including the last number.

Concept Snapshot

for (variable in start..end) {
    // code to repeat
}

- Runs loop from start to end inclusive
- 'variable' takes each value in the range
- Loop stops after end value
- Simple way to repeat code fixed times

Full Transcript

This visual shows how a Kotlin for loop with a range works. The loop starts by setting a range from 1 to 3. Then, for each number in this range, it runs the loop body which prints the current number. The variable i takes values 1, 2, and 3 in order. After i=3, the next value 4 is outside the range, so the loop stops. This example helps beginners see how the loop variable changes and when the loop ends.