Multiline strings with trimIndent in Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of trimIndent on a multiline string

What is the output of this Kotlin code snippet?

Kotlin

val text = """
    Hello,
      Kotlin!
      Welcome to trimIndent.
    """.trimIndent()
println(text)

A Hello,\nKotlin!\nWelcome to trimIndent.

B |Hello,\n | Kotlin!\n | Welcome to trimIndent.

C Hello,\n Kotlin!\n Welcome to trimIndent.

D Hello,\n Kotlin!\n Welcome to trimIndent.

💡 Hint

trimIndent removes the common minimal indent from all lines.

The trimIndent function removes the smallest common indent from every line. The first line has a 4-space indent, while the second and third lines have 6-space indents. It removes 4 spaces from each, keeping the relative indentation.

❓ Predict Output

intermediate

Effect of trimIndent on uneven indentation

What will be printed by this Kotlin code?

Kotlin

val poem = """
        Roses are red,
          Violets are blue,
        Kotlin is fun,
          And so are you.
    """.trimIndent()
println(poem)

A Roses are red,\nViolets are blue,\nKotlin is fun,\nAnd so are you.

B Roses are red,\n Violets are blue,\nRoses are red,\n And so are you.

C Roses are red,\n Violets are blue,\nKotlin is fun,\n And so are you.

D Roses are red,\n Violets are blue,\n Kotlin is fun,\n And so are you.

💡 Hint

trimIndent removes the smallest indent common to all lines.

The smallest indent common to all lines is 8 spaces. After removing it, lines with more indentation keep their extra spaces.

🔧 Debug

advanced

Why does this trimIndent code produce unexpected output?

Consider this Kotlin code: val message = """ Hello, World! """.trimIndent() println(message) Why does the output keep the extra spaces before 'World!'?

A Because trimIndent only removes the smallest common indent from all lines, and 'World!' line has more indentation.

B Because trimIndent removes all indentation from every line unconditionally.

C Because trimIndent only removes indentation if lines start with a margin prefix like '|'.

D Because trimIndent removes trailing spaces but not leading spaces.

💡 Hint

Think about how trimIndent calculates the indent to remove.

trimIndent finds the smallest indent common to all lines and removes that. Lines with more indentation keep their extra spaces.

📝 Syntax

advanced

Identify the syntax error in this multiline string usage

Which option contains a syntax error when using trimIndent with multiline strings in Kotlin?

Kotlin

val text = """
    Line one
    Line two
    Line three
""".trimIndent()

A

val text = """
    Line one
    Line two
    Line three
"".trimIndent()

B

)(tnednImirt."""
eerht eniL    
owt eniL    
eno eniL    
""" = txet lav

C

val text = """
    Line one
    Line two
    Line three
""".trimIndent()

D

al text = """
    Line one
    Line two
    Line three
""".trimIndent()

💡 Hint

Check the closing triple quotes and method call syntax.

Option A has only two double quotes to close the string, causing a syntax error. Triple quotes must be closed with exactly three double quotes.

🚀 Application

expert

How many lines does this trimmed multiline string contain?

Given this Kotlin code, how many lines does the resulting string contain after trimIndent is applied?

Kotlin

val data = """
        {
            "name": "Alice",
            "age": 30
        }
    """.trimIndent()

val linesCount = data.lines().size
println(linesCount)

A 6

B 5

C 4

D 7

💡 Hint

Count the lines inside the triple quotes after trimming indentation.

The string has 5 lines: '{', ' "name": "Alice",', ' "age": 30', '}', and an empty line is not present. trimIndent does not remove lines, only indentation.

Practice

1. What does the trimIndent() function do when used with multiline strings in Kotlin?

easy

A. It converts the string to uppercase.

B. It adds extra spaces at the beginning of each line.

C. It splits the string into a list of lines.

D. It removes the common leading whitespace from each line.

Solution

1. Step 1: Understand the purpose of trimIndent()

   The function trimIndent() removes the common leading whitespace from every line in a multiline string.

2. Step 2: Effect on multiline strings

   This makes the string output aligned neatly without extra indentation caused by code formatting.

3. Final Answer:

   It removes the common leading whitespace from each line. -> Option D

4. Quick Check:

   trimIndent() = removes leading spaces [OK]

Hint: trimIndent() cleans leading spaces for neat multiline strings [OK]

Common Mistakes:

• Thinking trimIndent() adds spaces instead of removing
• Confusing trimIndent() with uppercase conversion
• Assuming trimIndent() splits strings into lines

2. Which of the following is the correct syntax to create a multiline string with trimmed indentation in Kotlin?

easy

A. val text = """Hello\nWorld""".trimIndent()

B. val text = "Hello\nWorld".trimIndent()

C. val text = '''Hello\nWorld'''.trimIndent()

D. val text = ""Hello\nWorld"".trimIndent()

Solution

1. Step 1: Identify multiline string syntax

   Kotlin uses triple double quotes """ to create multiline strings.

2. Step 2: Apply trimIndent() correctly

   Calling trimIndent() on the multiline string removes common leading spaces.

3. Final Answer:

   val text = """Hello\nWorld""".trimIndent() -> Option A

4. Quick Check:

   Triple quotes + trimIndent() = correct syntax [OK]

Hint: Use triple quotes """ for multiline strings with trimIndent() [OK]

Common Mistakes:

• Using single quotes instead of triple quotes
• Trying to trimIndent() on a normal string
• Wrong quote count causing syntax errors

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

val text = """
    Kotlin
    is
    fun
""".trimIndent()
println(text)

medium

A. Kotlin
is
fun

B. Kotlin
is
fun

C. Kotlin
is
fun

D. Kotlin is fun

Solution

1. Step 1: Analyze the multiline string with indentation

   The string has 4 spaces before each line inside the triple quotes.

2. Step 2: Effect of trimIndent()

   trimIndent() removes the common 4-space indentation from all lines.

3. Final Answer:

   Kotlin is fun -> Option C

4. Quick Check:

   trimIndent() removes leading spaces = clean lines [OK]

Hint: trimIndent() removes common leading spaces from all lines [OK]

Common Mistakes:

• Expecting original indentation to remain
• Confusing trimIndent() with trim() which removes only ends
• Thinking output is a single line string

4. Identify the error in this Kotlin code snippet using multiline strings and trimIndent():

val message = """
  Hello
    World
"".trimIndent()
println(message)

medium

A. Missing one double quote in the closing triple quotes.

B. The closing triple quotes should be """ not "".

C. No error; code runs and prints correctly.

D. Incorrect use of trimIndent() on a non-multiline string.

Solution

1. Step 1: Check triple quote syntax

   Multiline strings require triple double quotes """ at start and end.

2. Step 2: Identify the closing quotes

   The code uses only two double quotes "" at the end, which is invalid syntax.

3. Step 3: Correct the closing quotes

   It should be """ to properly close the multiline string.

4. Final Answer:

   The closing triple quotes should be """ not "". -> Option B

5. Quick Check:

   Triple quotes must match at start and end [OK]

Hint: Always close multiline strings with triple quotes """ [OK]

Common Mistakes:

• Using two quotes instead of three to close multiline strings
• Assuming trimIndent() fixes quote errors
• Confusing trimIndent() with trimming quotes

5. You want to create a multiline string in Kotlin that shows a list of fruits without extra indentation in the output. Which code snippet correctly achieves this using trimIndent()?

hard

A. val fruits = """
- Apple
- Banana
- Cherry
""".trimIndent()
println(fruits)

B. val fruits = """
- Apple
- Banana
- Cherry
""".trimIndent()
println(fruits)

C. val fruits = """
- Apple
- Banana
- Cherry
""".trimIndent()
println(fruits)

D. val fruits = "- Apple\n- Banana\n- Cherry".trimIndent()
println(fruits)

Solution

1. Step 1: Understand trimIndent() effect on indentation

   trimIndent() removes the common leading spaces from all lines, aligning text properly.

2. Step 2: Check each option's indentation

   val fruits = """ - Apple - Banana - Cherry """.trimIndent() println(fruits) has consistent 4-space indentation on each line, so trimIndent() will remove it neatly.

3. Step 3: Evaluate other options

   val fruits = """ - Apple - Banana - Cherry """.trimIndent() println(fruits) has uneven indentation, so trimIndent() removes nothing and leaves extra spaces on some lines. val fruits = """ - Apple - Banana - Cherry """.trimIndent() println(fruits) has uneven indentation, so trimIndent() won't align all lines properly. val fruits = "- Apple\n- Banana\n- Cherry".trimIndent() println(fruits) is a normal string, trimIndent() has no effect.

4. Final Answer:

   val fruits = """ - Apple - Banana - Cherry """.trimIndent() println(fruits) -> Option A

5. Quick Check:

   Consistent indentation + trimIndent() = neat output [OK]

Hint: Use consistent indentation inside triple quotes before trimIndent() [OK]

Common Mistakes:

• Using uneven indentation causing partial trimming
• Not using triple quotes for multiline strings
• Expecting trimIndent() to fix uneven spaces