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Python

Puffy wuff
Puffy wuff
9,573 Points
Posted by Puffy wuff
Puffy wuff
9,573 Points

Python scope question

Why does this work:

def outer():
    x = 100
    def inner():
        print(x)
    inner()

outer()

But not this:

def outer():
    x = 100
    def inner():
        x += 10
        print(x)
    inner()

outer()

I don't understand why I can print x from the outer scope but not update it.

1 Answer

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

The "print" is simply accessing the variable from the outer scope.

But when you make an assignment, Python takes that to mean that a new variable should be created in the current scope. But "+=" is a special kind of assignment that also accesses the current value, so it doesn't work with variables being created in the same statement.