【发布时间】：2019-01-22 23:11:09
【问题描述】：
当尝试检索第二个选项的解密密码时，无论输入的网站是否真实，我都无法阻止程序打印Does Not Compute。当它不真实时它会打印两次，所以这让我相信它正在打印for i in the range(len(passwords))，即 2。
如何让它只打印一次密码或Does Not Compute 而不再重复它？我正在尝试检查输入是否等于网站，但它仍然会重复打印两次。
import csv
import sys
# The password list - We start with it populated for testing purposes
passwords = [["yahoo", "XqffoZeo"], ["google", "CoIushujSetu"]]
# The password file name to store the passwords to
passwordFileName = "samplePasswordFile"
# The encryption key for the caesar cypher
encryptionKey = 16
# Caesar Cypher Encryption
def passwordEncrypt(unencryptedMessage, key):
# We will start with an empty string as our encryptedMessage
encryptedMessage = ""
# For each symbol in the unencryptedMessage we will add an encrypted symbol into the encryptedMessage
for symbol in unencryptedMessage:
if symbol.isalpha():
num = ord(symbol)
num += key
if symbol.isupper():
if num > ord("Z"):
num -= 26
elif num < ord("A"):
num += 26
elif symbol.islower():
if num > ord("z"):
num -= 26
elif num < ord("a"):
num += 26
encryptedMessage += chr(num)
else:
encryptedMessage += symbol
return encryptedMessage
def loadPasswordFile(fileName):
with open(fileName, newline="") as csvfile:
passwordreader = csv.reader(csvfile)
passwordList = list(passwordreader)
return passwordList
def savePasswordFile(passwordList, fileName):
with open(fileName, "w+", newline="") as csvfile:
passwordwriter = csv.writer(csvfile)
passwordwriter.writerows(passwordList)
prompt_msg = """
What would you like to do:
1. Open password file
2. Lookup a password
3. Add a password
4. Save password file
5. Print the encrypted password list (for testing)
6. Quit program
Please enter a number (1-4)
"""
while True:
print(prompt_msg)
choice = input()
if choice == "1": # Load the password list from a file
passwords = loadPasswordFile(passwordFileName)
elif choice == "2": # Lookup at password
print("Which website do you want to lookup the password for?")
for keyvalue in passwords:
print(keyvalue[0])
print("----")
passwordToLookup = input()
for i in range(len(passwords)):
print(f"i={i}, store_info={passwords[i]}, website={passwords[i][0]}")
if passwordToLookup == passwords[i][0]:
password = passwordEncrypt(passwords[i][1], -(encryptionKey))
print(f"=> The password is {password}.")
else:
print("=> Does not compute!")
elif choice == "3":
print("What website is this password for?")
website = input()
print("What is the password?")
unencryptedPassword = input()
unencryptedPassword = passwordEncrypt(unencryptedPassword, encryptionKey)
newList = [website, unencryptedPassword]
passwords.append(newList)
print("Your password has been saved.")
elif choice == "4": # Save the passwords to a file
savePasswordFile(passwords, passwordFileName)
elif choice == "5": # print out the password list
for keyvalue in passwords:
print(", ".join(keyvalue))
elif choice == "6": # quit our program
sys.exit()
print()
print()
####### YOUR CODE HERE ######
# You will need to find the password that matches the website
# You will then need to decrypt the password
#
# 1. Create a loop that goes through each item in the password list
# You can consult the reading on lists in Week 5 for ways to loop through a list
#
# 2. Check if the name is found. To index a list of lists you use 2 square backet sets
# So passwords[0][1] would mean for the first item in the list get it's 2nd item (remember, lists start at 0)
# So this would be 'XqffoZeo' in the password list given what is predefined at the top of the page.
# If you created a loop using the syntax described in step 1, then i is your 'iterator' in the list so you
# will want to use i in your first set of brackets.
#
# 3. If the name is found then decrypt it. Decrypting is that exact reverse operation from encrypting. Take a look at the
# caesar cypher lecture as a reference. You do not need to write your own decryption function, you can reuse passwordEncrypt
#
# Write the above one step at a time. By this I mean, write step 1... but in your loop print out every item in the list
# for testing purposes. Then write step 2, and print out the password but not decrypted. Then write step 3. This way
# you can test easily along the way.
#
【问题讨论】：
-
你听说过字典吗？
-
我听说过，是的，但从未使用过。目前正在阅读它们。
-
只是想知道。它们在这里很有用，但不是必需的。
标签： python python-3.x loops iteration string-length