Python 3.x: AttributeError: 'str' object has no attribute 'append'

Question

I am trying to write a short script that will convert a word or sentence into it's alphabetical value, and then jump forward 5 values, and print the result as a string. For e.g.

['a', 'b', 'c']

Should change to...

'102 103 104'

However, I only get the above error. The code in question:

def enc(input, output, seq, str_int):
     input = input.lower()
     output = []
     for char in input:
         num = ord(char) + 5
         str_int = str(num)
         output.append(str_int)
         output = seq.join(output)
     return output
print(enc("hello", [], ' ', ' '))

I'm sure I'm just missing something really obvious. Thanks.

you are converting output = seq.join(output) output to string that is why the problem occurs — The6thSense
– The6thSense, Commented Oct 5, 2015 at 7:09
Yes, it was meant to be a list originally, but then changed to a string afterwards, to print. — MRIG
– MRIG, Commented Oct 5, 2015 at 7:10
it should indented straight with return statement or you could remove output = seq.join(output) and type return seq.join(output) your problem is due to wrong indentation — The6thSense
– The6thSense, Commented Oct 5, 2015 at 7:12

Anand S Kumar · Accepted Answer · 2015-10-05 07:13:54Z

2

The issue occurs because of the line -

output = seq.join(output)

According to the indentation , this is inside the for loop, and hence inside the for loop, you are changing the output variable to str (string) , after that when you try to do output.append() , it errors out. This is the main cause of the issue.

I am guessing you actually only intended to do this outside the loop , after completely creating the output list. But you really don't need to set it back , you can simply do -

def enc(input, output, seq, str_int):
     input = input.lower()
     for char in input:
         num = ord(char) + 5
         str_int = str(num)
         output.append(str_int)
     return seq.join(output)

Demo -

>>> def enc(input, output, seq, str_int):
...      input = input.lower()
...      for char in input:
...          num = ord(char) + 5
...          str_int = str(num)
...          output.append(str_int)
...      return seq.join(output)
...
>>> print(enc("hello", [], ' ', ' '))
109 106 113 113 116

answered Oct 5, 2015 at 7:13

Anand S Kumar

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1 Comment

MRIG Over a year ago

I realize my mistake now. Thanks again. :) I would accept your answer, but the timer is a thing.

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