Blog / November 24, 2017 / 1 min read / By Suneet Agrawal

‘in’ operator in Kotlin

‘in’ operator in Koltin is used to check the existence of particular variable or property in a Range or Collection whereas a ‘!in’ operator is just a not of ‘in’ operator and returns true if the condition is false. It can also be used to iterate over a range or collection.

1. ‘in’ operator in ‘if’ condition

val count = 5;
if (count in 1..10 && count !in 5..7) {
    print(Number is between range 1 to 10 but not between 5 to 7)
}

val array: IntArray = intArrayOf(1, 2, 3, 4, 5)
if (count in array) {
    print(Number is present in property array)
}

2. ‘in’ operator in ‘when’ condition

when (count) {
   in 11..20 -> print(Number is between 10 and 20 including both)
   !in 21..30 -> print(Number is not between 21 to 30)
   in array -> print(Number is present in property array)
   !in array -> print(Number is not present in property array)
}

3. ‘in’ operator in ‘for’ loop

for (item in 1..10){
    print(iterates loop from 1 to 10)
}

for (item in array){
    print(iterates all items in array)
}
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