Print and println output in Kotlin - Time & Space Complexity

Time Complexity: Print and println output

O(n)

Understanding Time Complexity

Let's explore how the time taken by print and println commands changes as we print more items.

We want to know how the program's running time grows when printing more lines.

Scenario Under Consideration

Analyze the time complexity of the following code snippet.

fun printNumbers(n: Int) {
    for (i in 1..n) {
        println(i)
    }
}

This code prints numbers from 1 up to n, each on its own line.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: The loop runs and calls println once per number.
• How many times: Exactly n times, where n is the input size.

How Execution Grows With Input

As n grows, the number of print actions grows the same way.

Input Size (n)	Approx. Operations
10	10 print calls
100	100 print calls
1000	1000 print calls

Pattern observation: The work grows directly in step with the number of items printed.

Final Time Complexity

Time Complexity: O(n)

This means the time to print grows in a straight line as you print more lines.

Common Mistake

[X] Wrong: "Printing multiple lines happens instantly or in constant time regardless of how many lines."

[OK] Correct: Each print takes time, so more lines mean more total time, growing with the number of lines.

Interview Connect

Understanding how simple loops like printing scale helps you explain program speed clearly and confidently.

Self-Check

"What if we used print instead of println inside the loop? How would the time complexity change?"

Practice

1. What is the main difference between print and println in Kotlin?

easy

A. print outputs only numbers; println outputs only text.

B. print adds a newline after output; println outputs text without a newline.

C. print outputs text without a newline; println adds a newline after output.

D. print is used for debugging; println is used for user messages.

Solution

1. Step 1: Understand print behavior

   print outputs text exactly as given and stays on the same line.

2. Step 2: Understand println behavior

   println outputs text and then moves the cursor to the next line.

3. Final Answer:

   print outputs text without a newline; println adds a newline after output. -> Option C

4. Quick Check:

   print no newline, println newline = A [OK]

Hint: Remember: println adds a line break, print does not [OK]

Common Mistakes:

• Confusing which function adds a newline
• Thinking print adds a newline
• Assuming println outputs only numbers

2. Which of the following is the correct syntax to print "Hello" and then move to a new line in Kotlin?

easy

A. println("Hello")

B. print("Hello")

C. println Hello

D. println["Hello"]

Solution

1. Step 1: Check syntax correctness

   Only println("Hello") uses correct function call syntax with parentheses and quotes.

2. Step 2: Verify output behavior

   println("Hello") prints "Hello" and moves to a new line automatically.

3. Final Answer:

   println("Hello") -> Option A

4. Quick Check:

   Correct syntax with println = A [OK]

Hint: Use parentheses and quotes exactly for print/println [OK]

Common Mistakes:

• Missing parentheses around arguments
• Using square brackets instead of parentheses
• Omitting quotes around strings

3. What will be the output of the following Kotlin code?

print("Hi")
println(" there")
print("Welcome")

medium

A. Hi there
Welcome

B. Hi
there
Welcome

C. Hi there Welcome

D. Hi there
Welcome

Solution

1. Step 1: Trace first print statement

   print("Hi") outputs "Hi" without newline.

2. Step 2: Trace println statement

   println(" there") outputs " there" and moves to next line.

3. Step 3: Trace last print statement

   print("Welcome") outputs "Welcome" on the new line.

4. Final Answer:

   Hi there Welcome -> Option D

5. Quick Check:

   print no newline, println newline = D [OK]

Hint: Remember print stays on line; println moves to next line [OK]

Common Mistakes:

• Assuming print adds newline
• Ignoring space in " there"
• Thinking all output is on one line

4. Identify the error in this Kotlin code snippet:

print("Hello")
println "World"

medium

A. Missing parentheses in println call

B. Missing quotes around Hello

C. print cannot be used without println

D. No error, code runs fine

Solution

1. Step 1: Check syntax of print statement

   print("Hello") is correct with parentheses and quotes.

2. Step 2: Check syntax of println statement

   println "World" is missing parentheses around the argument, which is required in Kotlin.

3. Final Answer:

   Missing parentheses in println call -> Option A

4. Quick Check:

   Function calls need parentheses = B [OK]

Hint: Always use parentheses for function calls in Kotlin [OK]

Common Mistakes:

• Omitting parentheses in function calls
• Thinking print needs println to work
• Confusing quotes usage

5. You want to print the numbers 1, 2, and 3 on the same line separated by spaces, then print "Done" on the next line. Which Kotlin code achieves this?

hard

A. print("1 2 3")
print("Done")

B. print("1 2 3")
println("Done")

C. print("1 ")
print("2 ")
print("3\n")
println("Done")

D. println("1")
println("2")
println("3")
print("Done")

Solution

1. Step 1: Print numbers on same line with spaces

   Using print("1 2 3") outputs "1 2 3" on the same line.

2. Step 2: Print "Done" on next line

   println("Done") prints "Done" and moves to the next line.

3. Final Answer:

   print("1 2 3") println("Done") -> Option B

4. Quick Check:

   Use print for same line, println for new line = A [OK]

Hint: Use print for same line, println to move to next line [OK]

Common Mistakes:

• Using println for each number causing new lines
• Using print after println without newline
• Adding \n inside print incorrectly