for循环中python变量的范围 [英] Scope of python variable in for loop

问题描述

这是我遇到问题的 Python 代码:

 for i in range (0,10):如果我==5:我+=3打印我

我希望输出是:

<预><代码>0123489

然而，解释器吐了:

<预><代码>0123486789

我知道 for 循环在 C 中为变量创建了一个新的作用域，但对 Python 一无所知.为什么i的值在Python的for循环中没有变化，有什么补救方法可以得到预期的输出?

解决方案

for循环遍历range(10)中的所有数字，即[0,1,2,3,4,5,6,7,8,9].
您更改 i 的 当前 值不会影响范围内的下一个值.

您可以通过 while 循环获得所需的行为.

i = 0当我 <10:# 随心所欲地做事和操作 `i`如果我==5:我+=3打印我# 不要忘记手动增加`i`我 += 1

Here's the Python code I'm having problems with:

for i in range (0,10):
    if i==5:
        i+=3
    print i

I expected the output to be:

0
1
2
3
4
8
9

However, the interpreter spits out:

0
1
2
3
4
8
6
7
8
9

I know that a for loop creates a new scope for a variable in C, but have no idea about Python. Why does the value of i not change in the for loop in Python, and what's the remedy to it to get the expected output?

解决方案

The for loop iterates over all the numbers in range(10), that is, [0,1,2,3,4,5,6,7,8,9].
That you change the current value of i has no effect on the next value in the range.

You can get the desired behavior with a while loop.

i = 0
while i < 10:
    # do stuff and manipulate `i` as much as you like       
    if i==5:
        i+=3

    print i

    # don't forget to increment `i` manually
    i += 1

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