Python加解密

Question

我试图加密一个用户输入信息。

我的代码：

#encrypt
user_input = input ("Enter string: ")
for char in user_input: #for every character in input
    cipher_num = (ord(char))+3%26 #using ordinal to find the number
    cipher= ''
    cipher = chr(cipher_num) # using chr to convert back to a letter
    cipher_text = '' #add all values to string
    cipher_text = (cipher_text+cipher)
print (cipher_text)

#decrypt
for char in cipher_text: #for every character in the encrpted text
    decrypt_num = (ord(char))-3%26
    decrypt= ''
    decrypt = chr(decrypt_num)
    decrypt_text = ''
    decrypt_text = (decrypt_text+decrypt)
print(decrypt_text)

我收到的输出是-

输入字符串: abc

F

C

为什么它只给出字符串中最后一个字符的加密值？

Answer 1

在你的循环中，你有

 cipher_text = '' #add all values to string

将cipher_text重置为空字符串。您的代码在每个循环中都写着：“空cipher_text并在其中放一个字符”。

您需要将这条线移出for循环。

您的代码应该如下所示：

cipher_text = ''  # initialise the string
for char in user_input:
    cipher_num = (ord(char))+3%26
    cipher= ''   # you don't need this line as the next one overwrites the variable
    cipher = chr(cipher_num)
    cipher_text = cipher_text + cipher
    # you can shorten the line above to: cipher_text += cipher

decrypt_text也是如此。

有许多方法可以简化这段代码，并使其更加pythonic，但这是另一个问题:)