How does this function definition work in python?

Question

I'm a newbie to Python, with a Java background. I came across the following function definition

def S(seq,i=0):
    print i
    if i==len(seq): 
        return 0    
    return S(seq,i+1)+seq[i]

What exactly does the i=0 do here, is it re-initialised to 0 each time? Because I notice that the value of i is incremented .

NPE · Accepted Answer · 2012-05-09 15:02:20Z

8

It provides the default value for the second argument.

The function can be called with either one or two arguments. If it's called with one, the second argument, i, defaults to zero.

answered May 9, 2012 at 15:02

NPE

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2 Comments

seeker Over a year ago

so that means that in this case seq will be a mandatory argument?

Steven Rumbalski Over a year ago

@KodeSeeker: Yes, seq would be a mandatory argument. Also, Python default arguments often trip up programmers coming from other languages. Make sure you read Default Parameter Values in Python.

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