Range 是 Scala 中一個常用的特性，具有以下特點：

• 支持 to 及 until，to 包含邊界上限，until 不包含邊界上限(兩者均包含邊界下限)
• 支持 Int、Long、Float、Double、Char、BigInt、BigDecimal
• 支持自定義步長及默認步長

接下來我們通過幾個例子來加深對這幾個特性的印象

支持 to 及 until

scala> 1 to 10
res2: scala.collection.immutable.Range.Inclusive = Range(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

scala> 1 until 10
res3: scala.collection.immutable.Range = Range(1, 2, 3, 4, 5, 6, 7, 8, 9)

支持多種數(shù)據類型

Int

scala> 1 to 5
res11: scala.collection.immutable.Range.Inclusive = Range(1, 2, 3, 4, 5)

scala> 1 to 5 by 2
res12: scala.collection.immutable.Range = Range(1, 3, 5)

scala> 1 to 5 by 3
res13: scala.collection.immutable.Range = Range(1, 4)

Long

scala> 1L to 5L
res14: scala.collection.immutable.NumericRange.Inclusive[Long] = NumericRange(1, 2, 3, 4, 5)

scala> 1L to 5L by 2
res15: scala.collection.immutable.NumericRange[Long] = NumericRange(1, 3, 5)

scala> 1L to 5L by 2L
res16: scala.collection.immutable.NumericRange[Long] = NumericRange(1, 3, 5)

scala> 1L to 5L by 3L
res17: scala.collection.immutable.NumericRange[Long] = NumericRange(1, 4)

Float

scala> 1.0F to 5.0F by 1.0F
res9: scala.collection.immutable.NumericRange[Float] = NumericRange(1.0, 2.0, 3.0, 4.0, 5.0)

scala> 1.0F to 5.0F by 1.3F
res10: scala.collection.immutable.NumericRange[Float] = NumericRange(1.0, 2.3, 3.6, 4.8999996)

Double

scala> 1.0D to 5.0D by 1.0D
res24: scala.collection.immutable.NumericRange[Double] = NumericRange(1.0, 2.0, 3.0, 4.0, 5.0)

scala> 1.0D to 5.0D by 1.3D
res25: scala.collection.immutable.NumericRange[Double] = NumericRange(1.0, 2.3, 3.5999999999999996, 4.8999999999999995)

Char

scala> 'a' to 'e' by 1
res26: scala.collection.immutable.NumericRange[Char] = NumericRange(a, b, c, d, e)

scala> 'a' to 'e' by 2
res27: scala.collection.immutable.NumericRange[Char] = NumericRange(a, c, e)

BigInt

scala> BigInt(1) to BigInt(5)
res36: scala.collection.immutable.NumericRange.Inclusive[BigInt] = NumericRange(1, 2, 3, 4, 5)

scala> BigInt(1) to BigInt(5) by 2
res38: scala.collection.immutable.NumericRange[BigInt] = NumericRange(1, 3, 5)

BigDecimal

scala> BigDecimal(1.1) to BigDecimal(5.6) by 1.3
res41: scala.collection.immutable.NumericRange.Inclusive[scala.math.BigDecimal] = NumericRange(1.1, 2.4, 3.7, 5.0)

scala> BigDecimal(1.1) to BigDecimal(5.6) by 3.3
res42: scala.collection.immutable.NumericRange.Inclusive[scala.math.BigDecimal] = NumericRange(1.1, 4.4)

支持自定義步長及默認步長

在上一小節(jié)的很多例子中，都用 by 指定了自定義步長，所有的類型都支持指定自定義步長。但并不是所有的類型都有默認步長，只有以下類型具有默認步長：

• Int默認步長: 1
• Long默認步長: 1
• Char默認步長: 1
• BigInt默認步長: 1