Hello Kotlin 2024

$ apt-cache show kotlin
Package: kotlin
Architecture: all
Version: 1.3.31+~1.0.1+~0.11.12-2
...
Installed-Size: 286240
...
Homepage: https://kotlinlang.org
Description-en: cross-platform, general-purpose programming languagehttps://kotlinlang.org/
 Kotlin is a cross-platform, statically typed, general-purpose programming
 language with type inference. Kotlin is designed to interoperate fully with
 Java, and the JVM version of its standard library  depends on the Java Class
 Library, but type inference allows its syntax to be more concise.

$ sudo apt install -y kotlin
...
Setting up kotlin (1.3.31+~1.0.1+~0.11.12-2) ...

fun main() {
    println("Hello FAMILUG 2024!")
}

$ kotlinc main.kt
$ kotlin MainKt
Hello FAMILUG 2024!
$ find .
.
./META-INF
./META-INF/main.kotlin_module
./MainKt.class
./main.kt

$ file MainKt.class
MainKt.class: compiled Java class data, version 50.0 (Java 1.6)

$ xxd MainKt.class| head -n3
00000000: cafe babe 0000 0032 002b 0100 064d 6169  .......2.+...Mai
00000010: 6e4b 7407 0001 0100 106a 6176 612f 6c61  nKt......java/la
00000020: 6e67 2f4f 626a 6563 7407 0003 0100 046d  ng/Object......m

$ /usr/bin/time -v kotlin MainKt
Hello FAMILUG 2024!
    Command being timed: "kotlin MainKt"
    User time (seconds): 0.08
    System time (seconds): 0.02
    Percent of CPU this job got: 116%
    Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.10
    Average shared text size (kbytes): 0https://github.com/JetBrains/kotlin/releases/tag/v1.3.31
    Average unshared data size (kbytes): 0
    Average stack size (kbytes): 0
    Average total size (kbytes): 0
    Maximum resident set size (kbytes): 37888
    Average resident set size (kbytes): 0
    Major (requiring I/O) page faults: 0
    Minor (reclaiming a frame) page faults: 5296
    Voluntary context switches: 282
    Involuntary context switches: 13
    Swaps: 0
    File system inputs: 0
    File system outputs: 64
    Socket messages sent: 0
    Socket messages received: 0
    Signals delivered: 0
    Page size (bytes): 4096
    Exit status: 0

$ /usr/bin/time -v /usr/bin/python3.11 -c 'print("Hello FAMILUG!")' |& grep Maximum
    Maximum resident set size (kbytes): 8960

fun sum3(a: Int, b: Int, c: Int): Int {
    return a + b + c
}

fun main() {
    println("Hello FAMILUG 2024!")
    val sum = sum3(1,2,3)
    println("Tong cua 1+2+3 la ${sum}")
}

$ kotlinc main.kt
$ kotlin MainKt
Hello FAMILUG 2024!
Tong cua 1+2+3 la 6

def sum3(a: int, b: int, c: int) -> int:
    return a + b +c

def main():
    print("Hello FAMILUG 2024!")
    sum = sum3(1,2,3)
    print(f"Tong cua 1+2+3 la {sum}")

main()

# main.kt
fun pe01(): Int {
    var sum = 0
    for (i in 1..999) {
        if (i % 3 == 0 || i % 5 == 0) {
            sum += i
        }
    }
    return sum
}

fun pe01_functional(): Int {
    return (1..999)
        .filter({it -> it % 3 == 0 || it % 5 == 0}) // hoặc ngắn hơn: .filter({ it % 3 == 0 || it % 5 == 0 })
        .sum()
}


fun main() {
    println(pe01())
    println(pe01() == pe01_functional())
}

$ kotlinc main.kt
hvn@mini:kotlinplay $ kotlin MainKt
233168
true

# main.kt
import java.math.BigInteger

fun pe16(): Int {
    val p: BigInteger = 2.toBigInteger().pow(1000)
    return p.toString()
            .chars()
            .map({ it - '0'.toInt() })
            .sum()
}

fun main() {
    println("tong cac chu so cua 2**1000 la ${pe16()}".toUpperCase())
}

$ kotlinc main.kt
$ kotlin MainKt
TONG CAC CHU SO CUA 2**1000 LA 1366

$ sort -nk 3 /etc/passwd | head -n3
_apt:x:105:65534::/nonexistent:/usr/sbin/nologin
avahi-autoipd:x:110:119:Avahi autoip daemon,,,:/var/lib/avahi-autoipd:/usr/sbin/nologin
avahi:x:114:121:Avahi mDNS daemon,,,:/run/avahi-daemon:/usr/sbin/nologin

import java.io.File
import java.io.InputStream

fun main() {
    val inputStream: InputStream = File("/etc/passwd").inputStream()
    val lineList = mutableListOf<Int>()

    inputStream.bufferedReader().forEachLine(
        { it -> lineList.add(it.split(":")[2].toInt()) }
    )
    println(lineList.max())
}

$ kotlinc main.kt
$ kotlin MainKt
65534