Range operator (..) and in operator in Kotlin - Step-by-Step Execution

Concept Flow - Range operator (..) and in operator

Start

↓

Create range with ..

↓

Use in operator to check membership

↓

If true -> Execute block

↓

If false -> Skip block

↓

End

Create a range using .., then check if a value is inside it using in operator, and run code accordingly.

Execution Sample

Kotlin

val range = 1..5
val x = 3
if (x in range) {
    println("x is in range")
} else {
    println("x is not in range")
}

Check if x is inside the range from 1 to 5 and print a message.

Execution Table

Step	Action	Expression	Result	Output
1	Create range	1..5	Range from 1 to 5
2	Assign x	x = 3	x = 3
3	Check if x in range	3 in 1..5	true
4	If true, print	println("x is in range")		x is in range
5	End	-	-	-

💡 Checked x in range, condition true, printed message, program ends.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
range	-	1..5	1..5	1..5	1..5
x	-	-	3	3	3

Key Moments - 2 Insights

Why does 'x in range' return true when x equals 3?

Because the range 1..5 includes all numbers from 1 to 5, and 3 is inside that range as shown in execution_table step 3.

What happens if x is 6 instead of 3?

The condition 'x in range' would be false, so the else block would run, printing 'x is not in range'. This is similar to execution_table step 3 but with false result.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'range' after step 1?

A 1..5

B 3

C true

D x

💡 Hint

Check the 'Result' column in row with Step 1 in execution_table.

At which step does the program print 'x is in range'?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the 'Output' column in execution_table to find when the message appears.

If x was 0, what would be the result of 'x in range' at step 3?

A true

B false

C error

D null

💡 Hint

Refer to variable_tracker and execution_table step 3 logic about range membership.

Concept Snapshot

Range operator (..) creates a range from start to end inclusive.
Use 'in' operator to check if a value is inside the range.
Example: val r = 1..5; if (x in r) { ... }
'..' includes both ends.
'in' returns true if value is inside range, false otherwise.

Full Transcript

This example shows how to create a range using the .. operator in Kotlin, which includes all numbers from the start to the end value. We assign x the value 3 and then check if x is inside the range using the in operator. Since 3 is between 1 and 5, the condition is true and the program prints 'x is in range'. The execution table traces each step: creating the range, assigning x, checking membership, printing output, and ending. The variable tracker shows how 'range' and 'x' change during execution. Key moments clarify why the condition is true and what happens if x is outside the range. The quiz tests understanding of the range value, when output occurs, and behavior with different x values.