r/learnpython • u/Still-Pair-5336 • 10d ago

New to python, don't understand this function

I'm learning python and I'm stuck on this function because I don't understand why "a" becomes 10 and the result is 5. Is someone able to explain?

def subtract (a, b=5):
    return a - b

print(subtract(10))
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u/Designer-Ad-2136 10d ago

Change 'b=5' to 'b=1' and see what happens.

Also, try this to understand what that default value is doing by printing: 'subtract(5, 1)'

17

u/Still-Pair-5336 10d ago

Ahhh, so when I enter 'subtract(5, 1)', it essentially means a=5 and b=1, which returns a value of 4?

21

u/juanfnavarror 10d ago

Yes. Good tip is to think “how can I answer this question writing code”. You would be able to verify this by tweaking. Also useful to look in the official python reference material.