# ‘when’ operator in Kotlin

`var intNumber = 10 when (intNumber) {    1 -> print(“value is 1”)    2 -> print(“value is 2”)    else -> {       print(“value of intNumber is neither 1 nor 2”)    } }`
`This post was originally posted at https://agrawalsuneet.github.io/blogs/when-operator-in-kotlin/ and reposted on Medium on 11th Jan 2018.`
`fun calculateAreaOfCircle(radius: Float): Float {    return (22 * radius * radius) / 7 }fun calculateAreaOfSquare(sideLength: Float): Float {    return (sideLength * sideLength) }fun calculateArea(shape: Shape) : Float {    var area = when (shape) {       is Circle -> calculateAreaOfCircle( radius = 6f)       is Square -> calculateAreaOfSquare(sideLength = 10f)       else -> {          print(“invalid shape”)          return 0f       }    }   //use area for further use   return area }`
`var count = 100 when (count) {    in 0 until 100 -> {    //count is between 1 to 99    count++ }  else -> {    //count is greater than 99    //set it to 0    count = 0 }}`
`val boolValue : Boolean = false  when (boolValue) {    false -> {       print(“value is false”)    }    true -> {       print(“value is true”)    } }`
`val value = 100  when (value) {    0, 1 -> print(“x == 0 or x == 1”)    !in 10..20, !in 30..40 -> {       print(“not in 10 to 20 and 30 to 40”)    }    else -> print(“otherwise”) }`
` val value = 21 val initialPrimeNumbers = intArrayOf(2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47)  when (value) {    in 10..20 -> print(“in 10 to 20”)    !in 30 until 40 -> print(“not in 30 to 39”)    in initialPrimeNumbers -> print(“exist in array”)    else -> print(“not present anywhere”) }`
`val shape : Shape = Circle()  when (shape) {    is Circle -> print(“shape is a Circle class object”)    is Square -> print(“shape is a Square class object”)    else -> {       print(“invalid shape”)    } }`
`val num = 10 when {    isPrime(num) -> print(“num is a prime number”)    isComposite(num) -> print(“num is a composite number”)    else -> {       print(“num is neither prime nor composit”)    } }`

--

--

## More from Suneet Agrawal

https://agrawalsuneet.github.io/

Love podcasts or audiobooks? Learn on the go with our new app.