# Learn String Manipulation by Building a Cipher - Step 35 where is the error

### Tell us what’s happening:

Describe your issue in detail here.
where is the error

``````text = 'Hello World'
shift = 3

/* User Editable Region */

alphabet = 'abcdefghijklmnopqrstuvwxyz'
encrypted_text = ''

for char in text.lower():

index = alphabet.find(char)
new_index = index + shift
encrypted_text +=  alphabet[new_index]
print('char:', char, 'encrypted text:', encrypted_text)

/* User Editable Region */

``````

User Agent is: `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36`

### Challenge Information:

Learn String Manipulation by Building a Cipher - Step 35

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Since the addition assignment operator `+=` has not been explained yet, you are supposed to use the `+` operator in this step.

but they say `encrypted_text + alphabet[new_index]` to `encrypted_text` variable. what that means where i will store my varible value

If you already know how to use `+=`, I assume you know what it means.
`a += b` means `a = a + b`. You have to use this second form of the expression.

can you please give me the solution

I cannot give you the solution but I’ve almost done it. You have `encrypted_text`, what’s the problem with assigning `encrypted_text + alphabet[new_index]` to it?

but they give error
if i will use this formate
and assigna with encrypted_text

What kind of error are you talking about?

text = ‘Hello World’
shift = 3
alphabet = ‘abcdefghijklmnopqrstuvwxyz’
encrypted_text = ’ ’

for char in text.lower():

``````index = alphabet.find(char)
new_index = index + shift
encrypted_text + alphabet[new_index]

print('char:', char, 'encrypted text:', encrypted_text)
``````

see this is okay or not

You didn’t declare `encrypted_text`.

bro where i will declear encrypted_text after encrypted_text + alphabet[new_index]

You cannot use `encrypted` text before declaring it. I suggest you to reset the code and try again.

thanks bro i will solve it