Kengaytma funksiyalari

fun String.birinchiHarfKatta(): String =
    if (isEmpty()) this else this[0].uppercase() + substring(1)

fun Int.kvadrat(): Int = this * this

fun main() {
    println("malika".birinchiHarfKatta())
    println("".birinchiHarfKatta())
    println(7.kvadrat())
}

fun List<Int>.ortacha(): Double =
    if (isEmpty()) 0.0 else sum().toDouble() / size

fun String.faqatRaqamlar(): String = filter { it.isDigit() }

fun Int.soatgaAylantir(): String = "%02d:%02d".format(this / 60, this % 60)

fun main() {
    println(listOf(85, 92, 78).ortacha())
    println(emptyList<Int>().ortacha())
    println("+998 (90) 123-45-67".faqatRaqamlar())
    println(145.soatgaAylantir())
}

val String.ikkinchiHarf: Char?
    get() = if (length >= 2) this[1] else null

val <T> List<T>.ikkinchisi: T?
    get() = if (size >= 2) this[1] else null

val Int.juftmi: Boolean
    get() = this % 2 == 0

fun main() {
    println("Kotlin".ikkinchiHarf)
    println("K".ikkinchiHarf)
    println(listOf(10, 20, 30).ikkinchisi)
    println(4.juftmi)
    println(7.juftmi)
}

open class Hayvon
class It : Hayvon()

fun Hayvon.ovoz() = "noma'lum ovoz"
fun It.ovoz() = "Vov-vov!"

fun main() {
    val it: It = It()
    val hayvon: Hayvon = It()

    println(it.ovoz())
    println(hayvon.ovoz())
}

class Quti {
    fun salom() = "a'zo metod"
}

fun Quti.salom() = "kengaytma"

fun main() {
    println(Quti().salom())
}

fun String?.xavfsizUzunlik(): Int = this?.length ?: 0

fun String?.boshMi(): Boolean = this == null || this.isBlank()

fun main() {
    val bor: String? = "matn"
    val yoq: String? = null

    println(bor.xavfsizUzunlik())
    println(yoq.xavfsizUzunlik())
    println(yoq.boshMi())
    println("  ".boshMi())
    println("x".boshMi())
}

class Hisob(private val qoldiq: Int) {
    fun ochiqQoldiq() = qoldiq
}

fun Hisob.yetarlimi(summa: Int): Boolean = ochiqQoldiq() >= summa

fun main() {
    val h = Hisob(500000)
    println(h.yetarlimi(200000))
    println(h.yetarlimi(900000))
}

infix fun Int.gacha(oxiri: Int): List<Int> = (this..oxiri).toList()

data class Nuqta(val x: Int, val y: Int)

infix fun Nuqta.qoshish(boshqa: Nuqta) = Nuqta(x + boshqa.x, y + boshqa.y)

fun main() {
    println(1 gacha 5)
    println(Nuqta(1, 2) qoshish Nuqta(3, 4))

    println(1.gacha(5))
}

data class Pul(
    val miqdor: Int,
    val valyuta: String = "so'm"
) : Comparable<Pul> {
    operator fun plus(boshqa: Pul) = Pul(miqdor + boshqa.miqdor, valyuta)
    operator fun times(son: Int) = Pul(miqdor * son, valyuta)

    override fun compareTo(other: Pul) = miqdor.compareTo(other.miqdor)

    override fun toString() = "$miqdor $valyuta"
}

fun main() {
    val a = Pul(50000)
    val b = Pul(30000)

    println(a + b)
    println(a * 3)
    println(a > b)
    println(listOf(a, b).max())
}

fun String.toza(): String = trim().lowercase()

class Hisobot {
    fun Int.formatla(): String = "%,d".format(this)

    fun chiqar(summa: Int) = "Summa: ${summa.formatla()}"
}

fun main() {
    println("  SALOM  ".toza())
    println(Hisobot().chiqar(1500000))
}