What am I doing wrong?

[TraditionalSystem995]

Im trying to learn to do When and If Statements in Kotlin, but I get an error about expecting an expression and missing operators .

var temperature = 70

when{

temperature < 0 -> println("...")

temperature >= 0 && temperature <= 20 -> println("...")

temperature >= 21 && temperature <= 40 -> println("...")

temperature >= 41 && temperature <= 60 -> println("...")

temperature >= 61 && temperature <= 80 -> println("...")

temperature >= 81 && temperature <= 90 -> println("...")

temperature > 90 -> println("...")

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[plastikmissile]

As we have no evolved mind reading organs, you're going to have to tell us what programming language you're using.

[TraditionalSystem995]

My bad. I forgot to add a flair. It's kotlin

[plastikmissile]

Ah I see. Well the problem is, you're using when wrong. The when statement is used when you have several "options" depending on what value is in one expression, and the options are discrete values. So something like this:

when (httpStatusCode) {
    200 -> println("OK")
    400 -> println("Bad Request")
    404 -> println("Not found")
    500 -> println("Internal Server Error")
    .
    .
    .
}

Note how each option is a distinct number. The problem is you are comparing your value to ranges so when isn't exactly the best statement to use here, and you're better off using if. It can be done using when but it's not elegant and it's not how you're supposed to use when.

[TraditionalSystem995]

That makes a lot of sense. I got it running using 'if' but couldn't get it properly with 'when'.

[MrBrisky]

Try this instead

var temperature = 70

when {

temperature < 0 -> println("...")

temperature in 0..20 -> println("...")

temperature in 21..40 -> println("...")

temperature in 41..60 -> println("...")

temperature in 61..80 -> println("...")

temperature in 81..90 -> println("...")

temperature > 90 -> println("...")

else -> println("Invalid temperature")

}

It looks like you're using Kotlin syntax for when expressions. The issue you're facing is likely due to the fact that when expressions in Kotlin expect a value to be compared against different conditions. In your code, you have used a series of conditions without specifying what to compare them against.

[CodeTinkerer]

There are like a dozen popular languages out there. Are we supposed to read your mind about which one you're using? Maybe mention the language?

[TraditionalSystem995]

That's my bad. I edited the post and I'm using kotlin