Hacking Secret Ciphers with Python

Chapter 8 – The Transposition Cipher, Encrypting 105

For example, type in the following short program, save it as scope.py, and press F5 to run it:

Source code for scope.py

1. spam = 42


2. 
   


3. def eggs():


4. spam = 99 # spam in this function is local


5. print('In eggs():', spam)


6. 
   


7. def ham():


8. print('In ham():', spam) # spam in this function is global


9. 
   


10. def bacon():


11. global spam # spam in this function is global


12. print('In bacon():', spam)


13. spam = 0


14. 
    


15. def CRASH():


16. print(spam) # spam in this function is local


17. spam = 0


18. 
    


19. print(spam)


20. eggs()


21. print(spam)


22. ham()


23. print(spam)


24. bacon()


25. print(spam)


26. CRASH()

The program will crash when Python executes line 1 6 , and the output will look like this:

42
In eggs(): 99
42
In ham(): 42
42
In bacon(): 42
0
Traceback (most recent call last):
File "C:\scope.py", line 27, in
CRASH()
File "C:\scope.py", line 16, in CRASH