Can someone please help explain the step process in this coding.

Question

def f(x):
if x == 0:
return 0
return x + f(x - 1)

print(f(3))

The ‘f(x’ in line 4 is confusing me. Because I’m not to sure if that puts it through the function again all over again.

Answer 1

It's recurrence

We are again calling the function but by decreasing the value of x by 1

Until and unless x doesn't becomes zero it will keep on adding the value of x and then return it .

So the fxn will return 3+2+1 =6 but as x becomes Zero it returns 0 and then it returns 6 .

Answer 2

The function is a recursive function means return itself until the condition is not acceptable.
In your code, the beginning value is 3 and the condition is 0, the function decreases the value one by one and returns itself until the value becomes 0.

Running process:
Beginning value: 3
Return value: 3+f(2), 2 is greater than 0, so continue
Return value: 3+2+f(1), 1 is greater than 0, so continue
Return value: 3+2+1+f(0), 0 equals to 0, so the function stops to return itself.

I hope, it's clear enough.
Happy coding!