Help plis.

Question

def fact (n)
if n <=1
1
else
n*fact (n-1)
end
end.
here in second line if n <=1. what code is run when the if statement is true...

Answer 1

The last thing evaluated in a method gets returned to wherever the method was called from. Because there is nothing after the if...else...end, the value 1 is returned from the fact method when the n <= 1 is true. You can think of this:

def fact(n)
if n <=1
1 #last line of fact when n <= 1
else
n * fact(n-1) #last line when n > 1
end
end

the same as you would think of this:

def fact(n)
if n <=1
return 1
else
return n * fact(n-1)
end
end

So if the n <= 1 is true, it will return 1 to wherever the fact method was called from. This could be a puts statement like:

puts fact(1)

where the "fact(1)" becomes the returned value 1, or it could return to the fact method call from within the else section of a previous fact method call:

n * fact(n - 1) #same as fact(1) if n is 2

and this is the hardest part to understand about recursion. Hope this answers your original question!