Python 什么是“IndexError：列表索引超出范围”？
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What is 'IndexError: list index out of range'?
提问by Richard Dao
This is my code:
这是我的代码：
from tkinter import messagebox, simpledialog, Tk
def is_even(number):
return number % 2 == 0
def get_even_letters(message):
even_letters = []
for counter in range(0, len(message)):
if is_even(counter):
even_letters.append(message[counter])
return even_letters
def get_odd_letters(message):
odd_letters = []
for counter in range(0, len(message)):
if not is_even(counter):
odd_letters.append(message[counter])
return odd_letters
def swap_letters(message):
letter_list = []
if not is_even(len(message)):
message = message + 'x'
even_letters = get_even_letters(message)
odd_letters = get_odd_letters(message)
for counter in range(0, int(len(message)/2)):
letter_list.append(odd_letters[counter])
letter_list.append(even_letters[counter])
new_message = ''.join(letter_list)
return new_message
def get_task():
task = simpledialog.askstring('Task', 'Do you want to encrypt or decrypt?')
return task
def get_message():
message = simpledialog.askstring('Message', 'Enter the secret message')
return message
root = Tk()
while True:
task = get_task()
if task == 'encrypt':
message = get_message()
encrypted = swap_letters(message)
messagebox.showinfo('Ciphertext of the secret message is:', encrypted)
elif task == 'decrypt':
message = get_message()
decrypted = swap_letters(message)
messagebox.showinfo('Plain text of the secret message is: ', decrypted)
else:
break
root.mainloop()
Currently using IDLE, Python 3.6.3. Whenever I run the program, the first prompt works, 'encrypt', but when I get to the 'Enter the secret message' prompt, if I type anything with more than 2 letters, it gives me the error:
目前使用空闲，Python 3.6.3。每当我运行程序时，第一个提示都会起作用，“加密”，但是当我进入“输入秘密消息”提示时，如果我输入的任何内容超过 2 个字母，就会出现错误：
Traceback (most recent call last):
File "/Users/richarddao/Documents/secret_message.py", line 46, in <module>
encrypted = swap_letters(message)
File "/Users/richarddao/Documents/secret_message.py", line 28, in swap_letters
letter_list.append(even_letters[counter])
IndexError: list index out of range
What is IndexError: list index out of range? How do I fix this?
什么是 IndexError：列表索引超出范围？我该如何解决？
回答by Qwerty
Index Error: List index out of rangemeans you are trying to get an item in a list that doesn't exist.
Index Error: List index out of range意味着您正在尝试获取不存在的列表中的项目。
For Example, I have this list:
例如，我有这个列表：
["a","b","c"]
["a","b","c"]
So a is the 0th item, b is the 1st, and c is the 2nd.
所以a是第0项，b是第1项，c是第2项。
I can get b by doing ["a","b","c"][1]because it is the first item and I am calling for the first item with [1].
我可以通过这样做得到 b，["a","b","c"][1]因为它是第一个项目，我用 [1] 调用第一个项目。
An index error is what would happen if I tried to do this:
如果我尝试这样做会发生索引错误：
["a","b","c"][4]
["a","b","c"][4]
There is no 4th item, so it errors.
没有第四项，所以它出错了。
回答by Richard Dao
So, uh it turns out it was a really simple answer... I needed to remove an indent from Line 11.
所以，呃事实证明这是一个非常简单的答案......我需要从第 11 行中删除一个缩进。
return even_letters
RIP. Thanks for everyone's explanation.
撕裂。谢谢大家的解释。
