CODEWITHSUNDEEP
kotlin
birgersp
birgersp

Reputation: 4966

How do I compare a Short with an Int in Kotlin?

I have a Short variable that I need to check the value of. But the compiler complains that Operator '==' cannot be applied to 'Short' and 'Int' when I do a simple equals check:

val myShort: Short = 4
if (myShort == 4) // <-- ERROR
    println("all is well")

So what's the simplest, "cleanest" way to do this equals check?

Here are some things I tried.

The first one casts the 4 integer to a short (looks weird, invoking a function on a primitive number)

val myShort: Short = 4
if (myShort == 4.toShort())
    println("all is well")

The next one casts the short to an int (shouldn't be necessary, now I have two ints when I shouldn't really need any)

val myShort: Short = 4
if (myShort.toInt() == 4)
    println("all is well")

Upvotes: 8

Views: 8847

Answers (2)

Thomas Martin
Thomas Martin

Reputation: 768

You could also create an infix function instead of ==. I called it eq

infix fun Short.eq(i: Int): Boolean = this == i.toShort()

And you can use it like this

val myShort: Short = 4
if (myShort eq 4)
    println("all is well")

Upvotes: 3

hotkey
hotkey

Reputation: 148189

Basically, the 'cleanest' way to compare it with a small constant is myShort == 4.toShort().

But if you want to compare a Short with a wider-type variable, convert myShort instead to avoid the overflow: myShort.toInt() == someInt.

looks weird, invoking a function on a primitive number

But it does not actually call the functions, they are intrinsified and compiled to bytecode that operates the numbers in a way that is natural for JVM, for example, the bytecode for myShort == 4.toShort() is:

ILOAD 2      // loads myShort
ICONST_4     // pushes int constant 4
I2S          // converts the int to short 4
IF_ICMPNE L3 // compares the two shorts

See also: another Q&A concerning numeric conversions.

Upvotes: 12

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