Android Code Snippet Factorial Function (!n)

i had to get the factorial of a number but could not find a buildin function in b4x so i created a function for that.

Sub factorial(number As Int) As Int
    Dim returnNr As Int = number
    Do Until number <= 1
        number = number - 1
        returnNr = returnNr * number
    Loop
    Return returnNr
End Sub

use:

Log(factorial(6))

log: 720

 

[Erel]

Your code is better but it is still worth posting the recursive version as it is quite nice:

Sub Factorial(Number As Int) As Int
 If Number = 1 Then Return 1
 Return Number * Factorial(Number - 1)
End Sub

 

[ilan]

Your code is better but it is still worth posting the recursive version as it is quite nice:

Sub Factorial(Number As Int) As Int
 If Number = 1 Then Return 1
 Return Number * Factorial(Number - 1)
End Sub

really cool, i didnot knew that it is possible to do that with b4x. very smart coding

 

[JordiCP]

As factorial is defined for n>=0 but still 0!=1, it should be (for non-negative numbers)

Sub Factorial(Number As Int) As Int
 If Number=0 Then Return 1
 Return Number * Factorial(Number - 1)
End Sub

 

[advansis]

I prefer non-recursive functions, in this case is very simple to enroll it. Recursive functions increase memory and stack usage. Recursion in very elegant, but, in my own opinion, usually are not efficient

 

[Erel]

Recursion in very elegant, but, in my own opinion, usually are not efficient

You cannot talk about efficiency without a real context. It doesn't matter whether a task takes 0.2ms or 0.4ms. Recursion is a very important tool. Like all tools it has its advantages and disadvantages.

 

[advansis]

You cannot talk about efficiency without a real context. It doesn't matter whether a task takes 0.2ms or 0.4ms. Recursion is a very important tool. Like all tools it has its advantages and disadvantages.

You are right, Erel. Anyway, when possible I prefer the straigth-way. ;-) Recursion is sometimes misused