Question

我的Ceasar Chiper计划遇到了麻烦。

这是我到目前为止所做的：

def enchiper(s,n):
    '''
    This function takes a string(s) and an integer(n) and
    shifts the elements of s around the alphabet
    '''
    Alpha1 = 'abcdefghijklmnopqrstuvwxyz'
    Alpha2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    if 1 == len(s):
        if 'a' <= s[0] <= 'z':
            spot1 = myIndex(s[0],Alpha1)
            x = spot1 + n
            if 26 < x:
                y = x - 26
                return Alpha1[y]
            else:
                return Alpha1[x]
        elif 'A' <= s[0] <= 'Z':
            spot1 = myIndex(s[0],Alpha2)
            x = spot1 + n
            if 26 < x:
                y = x - 26
                return Alpha2[y]
            else:
                return Alpha2[x]
        else:
            return s[0]
    else:
        if 'a' <= s[0] <= 'z':
            spot1 = myIndex(s[0],Alpha1)
            y = spot1 + n
            if 26 < y:
                x = y - 26
                return Alpha1[x] + enchiper(s[1:],n)
            else:
                return Alpha1[y] + enchiper(s[1:],n)
        elif 'A' <= s[0] <= 'Z':
            spot1 = myIndex(s[0],Alpha2)
            y = spot1 + n
            if 26 < y:
                x = y - 26
                return Alpha2[x] + enchiper(s[1:],n)
            else:
                return Alpha2[y] + enchiper(s[1:],n)
        else:
            return s[0] + enchiper(s[1:],n)

def myIndex(element, sequence):
    ''' returns the number of times that an element appears in a list
    returns a random number from 0 to length of sequence if the element
    does not appear in the list
    Input: element is either an integer or string
    sequence is a list of strings and integers
    '''
    if 0 == len(sequence):
        return 0
    elif sequence[0] == element:
        return 0
    else:
        return 1 + myIndex(element, sequence[1:])

该程序运行良好，有时我输入的字符串给我一个＃34;字符串索引超出范围＆＃34;。例如：

>>> enchiper('hello',15)
Traceback (most recent call last):
  File "<pyshell#48>", line 1, in <module>
    enchiper('hello',15)
  File "/Users/spencerzanardi/Documents/hw3pr2.py", line 41, in enchiper
    return Alpha1[y] + enchiper(s[1:],n)
  File "/Users/spencerzanardi/Documents/hw3pr2.py", line 41, in enchiper
    return Alpha1[y] + enchiper(s[1:],n)
  File "/Users/spencerzanardi/Documents/hw3pr2.py", line 41, in enchiper
    return Alpha1[y] + enchiper(s[1:],n)
IndexError: string index out of range

另外，我在我的程序中使用递归。我不允许使用循环

Answer 1

当我在y中打印Alpha1[y]时，我弄清了你的程序，我得到了26个。确实Alpha1（或者2）从0开始索引。尝试更改{{1}的所有出现次数1}}和if 26 < x: if 26 < y:和if 26 <= x:，它应该有效。

修改

不是您的问题，但是当第一个if 26 <= y:大于26时您的程序失败了，您应该考虑在函数开头使用模数。（例如n）

Answer 2

问题是您正在使用索引26，而数组Alpha1和Alpha2的索引从0到25.在特定的调用enchiper('hello',15)中，问题是字母l位于第11位。当您添加15时，您将得到26个。然后，条件26 < y将不得到满足，因此您将尝试返回Alpha1[26]，不存在。如果您按something > 26更改something >= 26的每一次出现，那么您的代码就会工作。

Answer 3

def encipher(s, n):
   diff = ord('Z') - ord('A')
   if len(s) == 1:
      num = ord(s)
      num += n % diff

      if s.isupper():
         if num > ord('Z'):
            num -= diff
         elif num < ord('A'):
            num += diff
      elif s.islower():
         if num > ord('z'):
            num -= diff
         elif num < ord('a'):
            num += diff
      return chr(num)

   return encipher(s[0], n) + encipher(s[1:], n)

Answer 4

虽然这不是大写/小写（虽然快速上或下，但它会）

def encyp(string,shift):
        Alpha1 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
        c=string[0]
        pos=Alpha1.find(c)
        pos=(pos+shift)%26
        if len(string)==1:
            return Alpha1[pos]
        else:
            return encyp(string[0], shift) +  encyp(string[1:], shift)

你可以缩短它......

蟒蛇。字符串索引超出范围。 Ceasar Cipher

4 个答案: