如何从单个元素列表中移除一个字符？

Question

这里是我的代码：

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

的箭头标记线是我尝试删除在中间列表中的最后一个字符。有些东西似乎不起作用...

Answer 1

在python中，字符串是不可变的。你将不得不设置修剪字符串返回到原始字符串：

intermediate = intermediate[:-1] 

而且，请注意，当您返回opposite，它不会是一个字符串，这将是字符的列表。你可以将其转换为字符串，像这样：

return ''.join(opposite) 

编辑：

好了，所以在观看你的代码，你有超过一个语法错误更多：

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 

所以一起，你想要的东西，如：

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

编辑2：此外，为了避免这样的困惑，我会坚持到只有串或仅列出，在这种情况下，没有必要列出所有：

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