Question

def encrypt(message):
ciphertext = ""
for x in message:
number = ord(x)
number = number - ord('A')
number = (number + 13)
number = number % 26
number = number + ord('A')
letter = chr(number)
ciphertext=ciphertext + letter
return (ciphertext)
message = "DIVINE" #QVIVAR
print(encrypt(message))

what changes can i make

Answer 1

The function you've provided performs a basic form of a Caesar cipher encryption with a shift of 13. However, it does not handle characters outside of the uppercase 'A' to 'Z' range, nor does it account for lowercase letters or non-alphabetic characters.

Here’s an enhanced version of your `encrypt` function that includes these considerations:

1. It checks if the characters are uppercase and lowercase letters.
2. It retains other characters unchanged (like spaces, punctuation, etc.).
3. It adjusts the shifting logic for both uppercase and lowercase letters.

Below is the revised version of the code:

```python
def encrypt(message):
ciphertext = ""
for x in message:
if 'A' <= x <= 'Z': # Check for uppercase letters
number = ord(x)
number = number - ord('A')
number = (number + 13)
number = number % 26
number = number + ord('A')
letter = chr(number)
elif 'a' <= x <= 'z': # Check for lowercase letters
number = ord(x)
number = number - ord('a')
number = (number + 13)
number = number % 26
number = number + ord('a')
letter = chr(number)
else:
letter = x # Non-alphabetic characters remain unchanged

ciphertext += letter # Append encrypted letter to ciphertext
return ciphertext

# Example usage
message = "Divine!" # This will become Qvivar!
print(encrypt(message))
```

### Key Changes and Features:
- **Character Case Handling:** The `encrypt` function now accounts for both uppercase (A-Z) and lowercase (a-z) letters, allowing the encryption function to work with mixed-case strings.
- **Preservation of Non-Alphabetical Characters:** Other characters such as punctuation (like `!`, `?`, or `,`) and spaces are retained in their original form in the output.

### Testing the Code:
You can test the code with various messages, including all uppercase, all lowercase, and mixed-case strings, as well as sentences that include punctuation or special characters to ensure it behaves as expected.