Learn Scala 3 Fast: Numeric Data Types

Now that you’ve seen strings and integers, a next good thing to know is that Scala comes with the following built-in numeric data types:

  • Byte
  • Short
  • Int
  • Long
  • Float
  • Double

And when you’re working with extremely large numbers you can also use:

  • BigInt
  • BigDecimal

Scala’s numeric data types

As a practical matter, until numbers get very large, most programmers generally use integers (Int) and double values (Double). Because of that, these are the defaults in Scala, as you can see in the REPL:

scala> val x = 42
val x: Int = 42

scala> val y = 42.0
val y: Double = 42.0

When I create x, Scala is smart enough to implicitly know that x is an Int, and when I create y, Scala also implicitly infers that it is a Double.

On the rare occasions that you might need to use the other numeric data types, declare them when you create your variables, like this:

val a: Byte = 1
val b: Long = 1
val c: Short = 1
val d: Float = 1.0

// you can also declare Int and Double this way,
// though it isn’t necessary:
val e: Int = 1
val f: Double = 1.0

Scala 3 also lets you declare numbers using underscore characters to make them more readable:

val a = 1_000        // Int
val b = 1_000_000    // Int
val c = 1_000_000L   // Long (created with the 'L' after the number)
val d = 1_234.56     // Double

This is a really useful feature when you’re working with large numbers.

BigInt and BigDecimal

When you need to create really, really large numbers, use the BigInt and BigDecimal data types:

val a = BigInt(1_234_567_890_123_456L)
val b = BigDecimal(123_456_789.012)

Use BigInt when you need integer-type numbers that are larger than Long, and BigDecimal when using very large floating-point numbers. Some developers also use BigDecimal for working with currency.

Scala data type sizes

For your reference, this table provides details about Scala’s data types:

Data Type  Definition

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)
           -9,223,372,036,854,775,808 to +9,223,372,036,854,775,807

Float      32-bit IEEE 754 single-precision float
           1.40129846432481707e-45 to 3.40282346638528860e+38
           (positive or negative)

Double     64-bit IEEE 754 double-precision float
           4.94065645841246544e-324 to 1.79769313486231570e+308
           (positive or negative)

Char       16-bit unsigned Unicode character
           (0 to 2^16-1, inclusive)
           0 to 65,535

String     a sequence of Char values

For more details on BigInt and BigDecimal, see their Scaladoc pages:


The exercises for this lesson are available here.

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