Originally Posted by Haze

when i say basic i mean basic it doesnt store the encrypted string in a file or anything it just prints out what it would be and all i intend it to do is swap a for b, b for c and so on then turn the string round backwards once its done that. and the decrypt would be turinng it round backwards again then changing b to a, c to b etc. anyway i have forgotten how to turn the string round backwards allthough i am pretty sure it has something to do with slicing like
a = pie
b = a[3:0]
print a
print b
with my expetced output being
pie
eip
and with the actual output being
pie
[this is a blank line]
anyway if someone can help with that or if you have a better method that would be great, anyway here is the code.

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 #simple encryption program
import os
list = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','a']
choice = 0
while choice != 2:
os.system("cls")
    print "Encryption/Decryption Program"
    print "-" * 10
    print "0 - Encrypt Text"
    print "1 - Decrypt Text"
    print "2 - Quit"
    choice = input("Choose: ")
    if choice == 0:
        print "Enter the string to be encrypted below"
        text = raw_input()
        for letter in range(1,27):
            letter2 = letter + 1
            text.replace(list[letter], letter2)
        print "Your text encrypted is",text                  
    elif choice == 1:
        print "Enter the string to be decyrpted below"
        text = raw_input()
        for letter in range(27,1):
            letter2 = letter - 1
            text.replace(list[letter], letter2)
        print "Your text decrypted is ",text
    elif choice == 2:
        print "Bye"
    else:
        print "Please enter either 0,1 or 2"
    raw_input()   
#End

#simple encryption program import os list = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','a'] choice = 0 while choice != 2: os.system("cls") print "Encryption/Decryption Program" print "-" * 10 print "0 - Encrypt Text" print "1 - Decrypt Text" print "2 - Quit" choice = input("Choose: ") if choice == 0: print "Enter the string to be encrypted below" text = raw_input() for letter in range(1,27): letter2 = letter + 1 text.replace(list[letter], letter2) print "Your text encrypted is",text elif choice == 1: print "Enter the string to be decyrpted below" text = raw_input() for letter in range(27,1): letter2 = letter - 1 text.replace(list[letter], letter2) print "Your text decrypted is ",text elif choice == 2: print "Bye" else: print "Please enter either 0,1 or 2" raw_input() #End

The problem is on this line

text.replace(list[letter], letter2)

and the error i get is

Traceback (most recent call last):
File "C:\Python25\Decrypt_Encrypt.py", line 20, in <module>
text.replace(list[letter], letter2)
TypeError: expected a character buffer object

i might just be using the wrong command or syntax or this might just not work at all and iam being a idiot but either way ied like help with this. thanks.

Originally Posted by jrcagle

But then, your code ran off the end of list because the highest value for letter2 is going to be 27, but the highest index in list is 26 (check me on those statements). So instead of range(1,27), we want 'range(26)'.

Originally Posted by Haze

sorry for double posting i cant find the edit button but i have found 1 problem with the program you have given me. when i try to encrpyt 'z' it will come out as b becuase it changes z to a then a to b. it works the same when decrypting the 'b' it comes out as z becuase it changes b to a then a to z.

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But then, your code ran off the end of list because the highest value for letter2 is going to be 27, but the highest index in list is 26 (check me on those statements). So instead of range(1,27), we want 'range(26)'.

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for i in range(1,10):
    print i

for i in range(1,10): print i

The output you would expect is just 1 to 10 but its actully 1 to 9.

Originally Posted by jrcagle

So: what if you re-wrote your algorithm so that each letter only gets touched once? I'll bet you could do that with a for loop, and maybe the functions ord() and chr().

Originally Posted by Haze

are you suggesting go through the list letter by letter and changing it to ascii then adding 1? then changing it back to a number using ord? what would happen then at z then when it would change it to [ maybe a if statement to see if it ascii code was that then insted of adding one chaning it to 97 for a?. ill see what i can do .