Scala Book

A Few Built-In Types


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)

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.

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