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kotlinlang

Is it necessary to specify the type in this case:
```var x = 10
var z: Long = x.toLong()
// or can I just write var z as:
var z = x.toLong()
// compiler should be able to infer the type, no?```

&gt; Is it necessary to specify the type in this case
no
&gt; `// compiler should be able to infer the type, no?`
yes

are you asking because you’re seeing behavior that suggests otherwise

I just saw this code in my book and it seemed redundant to specify the type, but as a beginner, I wasn't sure if this was best practice or how it should be written.

Is there a way to quickly check the type in Kotlin? I had to do this in the REPL and do a if (z is Long) { println("z is Long") }

I'm more familiar with JavaScript which has .typeof operator to check the type really quickly.

Screen Shot 2020-04-22 at 3.03.11 PM.png

with your text cursor placed after the variable name, bring up the intentions menu (alt/option+enter on macos) and select the appropriate type hints intention to see them at a glance

You just blew my mind. That's awesome. Thank you!

also, you can get the runtime type of a variable (albeit without generics) by getting its class reference, e.g.

```val foo = 42.toLong()
println(foo::class)   // class kotlin.Long```

That's really cool. This is going to speed up my learning a lot. Really appreciate it!

and it _might_ be worth mentioning that if you explicitly need a `Long` and are specifying a literal for it, you don’t have to call `.toLong()` - just append `L` to it: `val foo = 42L`. integer literals that are greater than `2³¹ - 1` are automatically allocated as `Long` s — see the docs: <https://kotlinlang.org/docs/reference/basic-types.html>

The book is good, but now I understand it better with your help :slightly_smiling_face: Thanks again!