Question

使用此程序取出空格，标点符号并使字母小写......

def pre_process(s): #Enter: "Jim's secret password."

    s= s.replace("'","")
    s= s.replace('.','')
    s= s.lower()
    s= s.replace(" ","")
    return s

如何加密邮件，使每个字母的数量等于字母表中相应的字母？例如， m 移位5次变为 r ，但 w 移位5次变为 b 。这是我目前的代码：

def shift(ch,k):    
    return chr(ord('a')+(ord(ch)-ord('a')+k) % 26)

Answer 1

def shift(ch, k):
    return chr(ord('a') + ((ord(ch) - ord('a')) + 
                           (ord(k) - ord('a'))) % 26)

一种解释：

def shift(ch, k):
    #
    # k_delta
    # ────>
    #
    # ch_delta                 k_delta
    # ────────────────────────>────>
    # a....f.........m....r....w..zab
    # ──────────────>────>         ┊
    # ch_delta       k_delta       ┊
    #                              ┊
    #                             %26

    ch_delta = ord(ch) - ord('a')
    k_delta = ord(k) - ord('a')
    return chr(ord('a') + (ch_delta + k_delta) % 26)

除非k发生变化，否则您可以使用str.translate来加速加密：

import string
message = 'mw'
key = 'f'
enc_table = string.maketrans(
    string.ascii_lowercase,
    ''.join(shift(c, key) for c in string.ascii_lowercase)
)
message.translate(enc_table) # -> 'rb'

我还建议将magic number 26替换为len(string.ascii_lowercase)。

解密可以使用相同的功能完成，但使用不同的键。它们之间的关系是enc_delta + dec_delta = 0 modulo 26。从此结果dec_delta = -enc_delta % 26。因此：

dec_k = chr(ord('a') + ((ord(enc_k) - ord('a'))) % 26)

Answer 2

你改变了问题。

根据旧问题：如何转移（＆＃39; w＆＃39; f＆＃39;）返回＆＃39; b＆＃39;？

从字母a获取第二个参数的差异，代码为diff = a2-start
通过添加差异从第一个参数获取下一个值，代码为next = a1+diff
检查下一个值是否大于alpha z。
如果不大于z，则新值为下一个值。
如果更大，则从alpha a
返回值字符。

代码：

def shift(ch,k):
    start = ord("a")
    end = ord("z")
    a1 = ord(ch)
    a2 = ord(k)

    diff = a2-start
    print "\ndiff:", diff
    next = a1+diff
    print "next value:", next
    if next>end:
        new = next-end-1
        print "new1:", new
        new = start + new  
    else:
        new = next

    print "new value:", new

    return chr(new)


rs = shift("w", "f")
print "w and f:", rs

rs = shift("e", "b")
print "e and b:", rs

rs = shift("z", "b")
print "z and b:", rs

rs = shift("x", "b")
print "x and b:", rs

输出：

vivek@vivek:~/Desktop/stackoverflow$ python 26.py 

diff: 5
next value: 124
new1: 1
new value: 98
w and f: b

diff: 1
next value: 102
new value: 102
e and b: f

diff: 1
next value: 123
new1: 0
new value: 97
z and b: a

diff: 1
next value: 121
new value: 121
x and b: y
vivek@vivek:~/D

Answer 3

解密/加密Python

代码：

def shift(ch, k):
    return chr(ord('a') + ((ord(ch) - ord('a')) + (ord(k) - ord('a'))) % 26)


def reshift(ch, k):
    tmp =  (ord(ch) - (ord(k) - ord('a')))
    if tmp<ord('a'):
        tmp = ord("a") +(26 - (ord("a") - tmp))
    return chr(tmp)

print "w and f:"
re = shift("w", "f")
print "Encryption:", re
re = reshift(re, "f")
print "Decrytion:", re

print "----------"
print "e and b"
re = shift("e", "b")
print "Encryption:", re
re = reshift(re, "b")
print "Decrytion:", re

print "----------"
print "z and b"
re = shift("z", "b")
print "Encryption:", re
re = reshift(re, "b")
print "Decrytion:", re

print "----------"
print "x and b"
re = shift("x", "b")
print "Encryption:", re
re = reshift(re, "b")
print "Decrytion:", re

输出：

vivek@vivek:~/Desktop/stackoverflow$ python 26.py 
w and f:
Encryption: b
Decrytion: w
----------
e and b
Encryption: f
Decrytion: e
----------
z and b
Encryption: a
Decrytion: z
----------
x and b
Encryption: y
Decrytion: x
vivek@vivek:~/Desktop/stackoverflow$

如何转换（＆＃39; w＆＃39; f＆＃39;）返回＆＃39; b＆＃39 ;?

3 个答案: