KOTLIN: Range

Sumber: https://www.tutorialspoint.com/kotlin/kotlin_ranges.htm

Kotlin range is defined by its two endpoint values which are both included in the range. Kotlin ranges are created with rangeTo() function, or simply using downTo or (. .) operators. The main operation on ranges is contains, which is usually used in the form of in and !in operators.

Rentang Kotlin ditentukan oleh dua nilai titik akhir yang keduanya termasuk dalam rentang. Rentang Kotlin dibuat dengan fungsi rangeTo(), atau cukup menggunakan operator downTo atau (. .). Operasi utama pada range adalah berisi, yang biasanya digunakan dalam bentuk operator in dan !in.

Example

1..10  // Range of integers starting from 1 to 10
a..z   // Range of characters starting from a to z
A..Z   // Range of capital characters starting from A to Z

Both the ends of the range are always included in the range which means that the 1..4 expression corresponds to the values 1,2,3 and 4.

Kedua ujung rentang selalu disertakan dalam rentang yang berarti bahwa ekspresi 1.4 sesuai dengan nilai 1,2,3 dan 4.

Creating Ranges using rangeTo()

To create a Kotlin range we call rangeTo() function on the range start value and provide the end value as an argument.

Untuk membuat rentang Kotlin, kami memanggil fungsi rangeTo() pada nilai awal rentang dan memberikan nilai akhir sebagai argumen.

Example

fun main(args: Array<String>) {
   for ( num in 1.rangeTo(4) ) {
     println(num)
   }
}

When you run the above Kotlin program, it will generate the following output:

Ketika Anda menjalankan program Kotlin di atas, itu akan menghasilkan output berikut:

1
2
3
4

Creating Ranges using .. Operator

The rangeTo() is often called in its operator form ... So the above code can be re-written using .. operator as follows:

RangeTo() sering disebut dalam bentuk operatornya ... Jadi kode di atas dapat ditulis ulang menggunakan .. operator sebagai berikut:

Example

fun main(args: Array<String>) {
   for ( num in 1..4 ) {
     println(num)
   }
}

When you run the above Kotlin program, it will generate the following output:

Ketika Anda menjalankan program Kotlin di atas, itu akan menghasilkan output berikut:

1
2
3
4

Creating Ranges using downTo() Operator

If we want to define a backward range we can use the downTo operator:

Jika kita ingin mendefinisikan rentang mundur, kita dapat menggunakan operator downTo:

Example

fun main(args: Array<String>) {
   for ( num in 4 downTo 1 ) {
     println(num)
   }
}

When you run the above Kotlin program, it will generate the following output:

Ketika Anda menjalankan program Kotlin di atas, itu akan menghasilkan output berikut:

4
3
2
1

Kotlin step() Function

We can use step() function to define the distance between the values of the range. Let's have a look at the following example:

Kita dapat menggunakan fungsi step() untuk menentukan jarak antara nilai-nilai rentang. Mari kita lihat contoh berikut:

Example

fun main(args: Array<String>) {
   for ( num in 1..10 step 2 ) {
     println(num)
   }
}

When you run the above Kotlin program, it will generate the following output:

Ketika Anda menjalankan program Kotlin di atas, itu akan menghasilkan output berikut:

1
3
5
7
9

Kotlin range of Characters

Ranges can be created for characters like we have created them for integer values.

Rentang dapat dibuat untuk karakter seperti kita telah membuatnya untuk nilai integer.

Example

fun main(args: Array<String>) {
   for ( ch in 'a'..'d' ) {
     println(ch)
   }
}

When you run the above Kotlin program, it will generate the following output:

Ketika Anda menjalankan program Kotlin di atas, itu akan menghasilkan output berikut:

a
b
c
d

Kotlin reversed() Function

The function reversed() can be used to reverse the values of a range.

Fungsi reversed() dapat digunakan untuk membalikkan nilai suatu range.

Example

fun main(args: Array<String>) {
   for ( num in (1..5).reversed() ) {
     println(num)
   }
}

When you run the above Kotlin program, it will generate the following output:

Ketika Anda menjalankan program Kotlin di atas, itu akan menghasilkan output berikut:

5
4
3
2
1

Kotlin until() Function

Example

fun main(args: Array<String>) {
   for ( num in 1 until 5 ) {
     println(num)
   }
}

When you run the above Kotlin program, it will generate the following output:

1
2
3
4

The last, first, step Elements

We can use first, last and step properties of a range to find the first, the last value or the step of a range.

Example

fun main(args: Array<String>) {
   println((5..10).first)
   println((5..10 step 2).step)
   println((5..10).reversed().last)
}

When you run the above Kotlin program, it will generate the following output:

5
2
5

Filtering Ranges

The filter() function will return a list of elements matching a given predicate:

Example

fun main(args: Array<String>) {
   val a = 1..10
   val f = a.filter { T -> T % 2 == 0 }
   
   println(f)
}

When you run the above Kotlin program, it will generate the following output:

[2, 4, 6, 8, 10]

Distinct Values in a Range

The distinct() function will return a list of distinct values from a range having repeated values:

Example

fun main(args: Array<String>) {
   val a = listOf(1, 1, 2, 4, 4, 6, 10)
   
   println(a.distinct())
}

When you run the above Kotlin program, it will generate the following output:

[1, 2, 4, 6, 10]

Range Utility Functions

There are many other useful functions we can apply to our range, like min, max, sum, average, count:

=Example

fun main(args: Array<String>) {
   val a = 1..10
   
   println(a.min())
   println(a.max())
   println(a.sum())
   println(a.average())
   println(a.count())
}

When you run the above Kotlin program, it will generate the following output:

1
10
55
5.5
10

Quiz Time (Interview & Exams Preparation)

Q 1 - Which of the following is true about Kotlin Ranges?

A - Kotlin range is a sequence of values defined by a start, an end, and a step.

B - Kotlin range can be created using the rangeTo() and downTo() functions or the .. operator.

C - We can use ranges for any comparable type.

D - All of the above

Q 2 - What will be the output of the following program:

fun main(args: Array<String>) {

  val a = 1..20
  
  println(a.average())

} A - This will print 10.5

B - This will raise just a warning

C - Compilation will stop with error

D - None of the above

Q 2 - What will be the output of the following program:

fun main(args: Array<String>) {

  val a = 1..20
  
  if( 3 in a){
     print( true )
  }else{
     print( false )
  }

} A - true

B - false

C - Compilation will stop with error

D - None of the above

Refernsi

• https://www.tutorialspoint.com/kotlin/kotlin_ranges.htm