코틀린스럽다 - 정현진

[currenjin]

data class User(val name: String, val age: Int)

class UserManagementSystem {
    private val users = mutableListOf<User>()

    fun addUser(name: String, age: Int) = this.users.add(User(name, age))

    fun getAdultUsers(): List<User> = this.users.filter { it.age >= 18 }

    fun printUserNames() = this.users.forEach { println(it.name) }

    fun calculateAverageAge(): Double = this.users.sumOf { it.age } / users.size.toDouble()

}

fun main() {
    val system = UserManagementSystem()

    system.addUser("옥순", 25)
    system.addUser("상철", 17)
    system.addUser("영철", 30)

    println("모든 사용자 이름:")
    system.printUserNames()

    println("\n성인 사용자:")
    system.getAdultUsers().forEach { println("${it.name} (${it.age}세)") }

    println("\n평균 나이: ${system.calculateAverageAge()}")
}