Kotlin Tutorial · Kotlin Basics · Lesson 3 of 31

Kotlin Syntax and Output

Statements, comments, println and print, and string templates for formatted output.

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Basic syntax

One statement per line, no semicolons needed.
// line comments and /* ... */ block comments (which can nest).
println(x) prints a value and a new line; print(x) prints without the new line.

print and println

fun main() {
    // Print a few values
    print("Loading")
    print("...")
    println(" done")
    println(42)
    println(3 * 7 + 1)
}

Output

Loading... done
42
22

Run this on your computer — see “Get Started” for setup.

String templates

$name inserts a variable and ${expression} inserts any expression. "%.2f".format(x) formats numbers.

String templates

fun main() {
    val name = "Ana"
    val items = listOf("mug", "teapot")
    val balance = 1234.5678
    println("$name has ${items.size} items")
    println("First item: ${items.first().uppercase()}")
    println("Balance: ${"%.2f".format(balance)} EUR")
}

Output

Ana has 2 items
First item: MUG
Balance: 1234.57 EUR

Run this on your computer — see “Get Started” for setup.

Test yourself

How do you insert the result of an expression into a string?

$(expression)
${expression}
{expression}
%expression%

Show answer

Answer: ${expression}

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