error saying variable is not defined in a function in python

Question

I am trying to write a simple function to take a char out of a user input in python but keep getting the following error:

    Traceback (most recent call last):
  File "C:/Users/chris/Desktop/Python_Stuff/replace.py", line 4, in <module>
    new= old.replace("*","")
NameError: name 'old' is not defined

This is my code:

def remove_char(old):
    old =input("enter a word that includes * ")
    return old #do I even need this?
new= old.replace("*","")
print (new)

Thanks in advance for the help!

Yes, you always need this. Since function returns values and procedures perform operations. — Mauro Baraldi
– Mauro Baraldi, Commented Mar 19, 2015 at 18:17

ForceBru · Accepted Answer · 2015-03-19 18:16:25Z

1

Your function's returning a value. Please do not ignore it.

def remove_char(old):
   old =input("enter a word that includes * ")
   return old

new= remove_char(old).replace("*","") 
print (new)

Yes, you may not need return:

old=None
def remove_char():
   global old
   old =input("enter a word that includes * ")

remove_char() # NOTE: you MUST call this first!
new= old.replace("*","") 
print (new)

Note: I agree with @jonrsharpe - the second example shows one of the ugliest ways to achieve what you want! You asked whether you can omit return - yes, but you'd better do not.

edited Mar 19, 2015 at 18:16

answered Mar 19, 2015 at 18:11

ForceBru

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4 Comments

jonrsharpe Over a year ago

Why on earth would you provide the global version?

ForceBru Over a year ago

@jonrsharpe, OP asked if it was possible to remove return - yes, it is - with globals

jonrsharpe Over a year ago

At the very least, you should point out that that is a terrible way of writing the program...

Mauro Baraldi Over a year ago

The wrong answer to this question is: "Because I can". The right version: True, why the hell I did that!?

overcomer · Accepted Answer · 2018-01-04 14:42:23Z

0

You can not use a method in old variable, because you never defined this variable before. (old is defined and visible just in the function, not outside). You do not really need a function to input the word. Try this:

old = raw_input('enter a word that includes * ')
new= old.replace("*","")
print (new)

edited Jan 4, 2018 at 14:42

answered Mar 19, 2015 at 18:31

overcomer

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1 Comment

Jackie_SAFC Over a year ago

Thanks, yeah I noticed I didn't need the function, I was just trying to gain a better understanding! I probably chose the wrong example. Thanks for the input!

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