LESSON 373 OF 414 · PROJECTS: COMMAND-LINE TOOLS

CLI Tool: cat v1 — Print Lines in Kotlin

Practice

Build a tiny version of the Unix cat command. Given a list of lines, return them joined by newline characters (\n) so they print one per line.

Lines can be blank, and the list can be empty (the result is then an empty string).

Function signature:

fun cat(lines: List<String>): String

Example:

Input: lines = ["hello", "world", "foo"]

Output: "hello\nworld\nfoo"

When printed:
hello
world
foo

Think of the output as one big String where each input line is separated from the next by a newline character. Kotlin's List has a method that glues all of its elements together with a chosen separator.

Call lines.joinToString("\n") — pass "\n" as the separator so each line ends up on its own line.

The full solution is a one-liner:

class Solution {
    fun cat(lines: List<String>): String {
        return lines.joinToString("\n")
    }
}

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CLI Tool: cat v1 — Print Lines in Kotlin

Cat V1 in Kotlin