遞歸在純功能編程中起著重要作用,Scala支持遞歸函數。 遞歸表示一個函數可以重複調用自身。
嘗試以下程式,它是一個很好的遞歸示例,它計算給定參數(數字)的階乘。
示例
object Demo {
def main(args: Array[String]) {
for (i <- 1 to 10)
println( "Factorial of " + i + ": = " + factorial(i) )
}
def factorial(n: BigInt): BigInt = {
if (n <= 1)
1
else
n * factorial(n - 1)
}
}
將上述程式保存在原始檔案:Demo.scala中,使用以下命令編譯和執行此程式。
$ scalac Demo.scala
$ scala Demo
Factorial of 1: = 1
Factorial of 2: = 2
Factorial of 3: = 6
Factorial of 4: = 24
Factorial of 5: = 120
Factorial of 6: = 720
Factorial of 7: = 5040
Factorial of 8: = 40320
Factorial of 9: = 362880
Factorial of 10: = 3628800