Avoiding Overflow

Question

This Stackoverflow post discusses the potential problem of a numeric overflow if not appending L to a number:

Here's an example from the REPL:

scala> 100000 * 100000 // no type specified, so numbers are `int`'s
res0: Int = 1410065408

One way to avoid this problem is to use L.

scala> 100000L * 100000L
res1: Long = 10000000000

Or to specify the number's types:

scala> val x: Long = 100000
x: Long = 100000

scala> x * x
res2: Long = 10000000000

What's considered the best practice to properly specify a number's type?

Answer 1

You should always use L if you are using a long. Otherwise, you can still have problems:

scala> val x: Long = 10000000000
<console>:1: error: integer number too large
       val x: Long = 10000000000
                     ^

scala> val x = 10000000000L
x: Long = 10000000000

The conversion due to type ascription happens after the literal has been interpreted as Int.