Scala - Recursion Functions

Recursion plays a big role in pure functional programming and Scala supports recursion functions very well. Recursion means a function can call itself repeatedly.

Try the following program, it is a good example of recursion where factorials of the passed number are calculated.

Example

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)
   }
}

Save the above program in Demo.scala. The following commands are used to compile and execute this program.

Command

\>scalac Demo.scala
\>scala Demo

Output

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