Question

I was wondering why i was getting this error for adding a letter to this string from a function.
local variable 'string' referenced before assignment

CODE

def update_string():
    string+='d'


string='s'

update_string()

Answer 1

There is nowhere for the old ‘string’ to come from in the local scope of your function, so python assumes you’re talking about the one from the outer scope.

Moreover, since strings are immutable the usual pattern is to create a new one and return it, so you might prefer to update your function interface to something more like:

def update_string(str_in):
  return str_in + 'd'

And then you would use it instead like:

my_string = update_string(my_string)