type: section layout: multipage-overview title: A Few Built-In Types description: A brief introduction to Scala's built-in types. partof: scala_book overview-name: Scala Book discourse: true num: 10 outof: 54 previous-page: type-is-optional next-page: two-notes-about-strings
Scala comes with the standard numeric data types you’d expect. In Scala all of these data types are full-blown objects (not primitive data types).
These examples show how to declare variables of the basic numeric types:
val b: Byte = 1
val x: Int = 1
val l: Long = 1
val s: Short = 1
val d: Double = 2.0
val f: Float = 3.0
In the first four examples, if you don’t explicitly specify a type, the number 1 will default to an Int, so if you want one of the other data types — Byte, Long, or Short — you need to explicitly declare those types, as shown. Numbers with a decimal (like 2.0) will default to a Double, so if you want a Float you need to declare a Float, as shown in the last example.
Because Int and Double are the default numeric types, you typically create them without explicitly declaring the data type:
val i = 123 // defaults to Int
val x = 1.0 // defaults to Double
The REPL shows that those examples default to Int and Double:
scala> val i = 123
i: Int = 123
scala> val x = 1.0
x: Double = 1.0
Those data types and their ranges are:
| Data Type | Possible Values |
|---|---|
| Boolean | true or false |
| Byte | 8-bit signed two’s complement integer (-2^7 to 2^7-1, inclusive) -128 to 127 |
| Short | 16-bit signed two’s complement integer (-2^15 to 2^15-1, inclusive) -32,768 to 32,767 |
| Int | 32-bit two’s complement integer (-2^31 to 2^31-1, inclusive) -2,147,483,648 to 2,147,483,647 |
| Long | 64-bit two’s complement integer (-2^63 to 2^63-1, inclusive) (-2^63 to 2^63-1, inclusive) |
| Float | 32-bit IEEE 754 single-precision float 1.40129846432481707e-45 to 3.40282346638528860e+38 |
| Double | 64-bit IEEE 754 double-precision float 4.94065645841246544e-324d to 1.79769313486231570e+308d |
| Char | 16-bit unsigned Unicode character (0 to 2^16-1, inclusive) 0 to 65,535 |
| String | a sequence of Char |
BigInt and BigDecimal
For large numbers Scala also includes the types BigInt and BigDecimal:
var b = BigInt(1234567890)
var b = BigDecimal(123456.789)
A great thing about BigInt and BigDecimal is that they support all the operators you’re used to using with numeric types:
scala> var b = BigInt(1234567890)
b: scala.math.BigInt = 1234567890
scala> b + b
res0: scala.math.BigInt = 2469135780
scala> b * b
res1: scala.math.BigInt = 1524157875019052100
scala> b += 1
scala> println(b)
1234567891
String and Char
Scala also has String and Char data types, which you can generally declare with the implicit form:
val name = "Bill"
val c = 'a'
Though once again, you can use the explicit form, if you prefer:
val name: String = "Bill"
val c: Char = 'a'
As shown, enclose strings in double-quotes and a character in single-quotes.