如何从单个元素列表中删除一个字符？

Question

这是我的代码：

def reverse(text):
   intermediate = []
   opposite = []
   intermediate.append(text)
   size = len(intermediate)
   while len(intermediate) > 0:
       opposite.append(intermediate[-1])
       intermediate[:-1]   `  <---
   return opposite

箭头标记的行是我尝试删除中间列表中的最后一个字符的位置。有些东西似乎不起作用......

Answer 1

在python中，字符串是不可变的。您必须将修剪后的字符串设置回原始字符串：

intermediate = intermediate[:-1]

另请注意，当您返回opposite时，它不会是字符串，而是字符列表。您可以将其转换为如下字符串：

return ''.join(opposite)

修改 的

好的，看看你的代码，你不仅仅是语法错误：

def reverse(text):
   intermediate = []
   opposite = []
   intermediate.append(text) # <-- this line makes intermediate a list with one element: ['input_text']
                             # you want intermediate = str(text) (cast it to make a copy)
                             # as it is, you will just pass this string from one list to another, and return
   size = len(intermediate)  # you don't need this
   while len(intermediate) > 0:
       opposite.append(intermediate[-1])
       intermediate[:-1]     # your string immutability problem
   return opposite           # your list/string confusion

总而言之，你想要的是：

def reverse(text):
   opposite = []
   intermediate = str(text)
   while len(intermediate) > 0:
       opposite.append(intermediate[-1])
       intermediate = intermediate[:-1]
   return ''.join(opposite)

编辑2： 另外，为了避免这种混淆，我会坚持只使用字符串或仅列表，在这种情况下，不需要列表所有：

def reverse(text):
   opposite = ''
   intermediate = str(text)
   while len(intermediate) > 0:
       opposite += intermediate[-1]
       intermediate = intermediate[:-1]
   return opposite