访问"for"循环中的索引? [英] Accessing the index in 'for' loops?

问题描述

如何在如下所示的for循环中访问索引?

ints = [8, 23, 45, 12, 78]
for i in ints:
    print('item #{} = {}'.format(???, i))

我想得到这个输出:

 item #1 = 8
item #2 = 23
item #3 = 45
item #4 = 12
item #5 = 78
 

当我使用for循环遍历它时，如何访问循环索引(在这种情况下为1到5)?

解决方案

使用其他状态变量，例如索引变量(通常在C或PHP等语言中使用)，被认为是非Python语言. /p>

更好的选择是使用内置函数 enumerate() ，适用于Python 2和3:

for idx, val in enumerate(ints):
    print(idx, val)

有关更多信息，请查看 PEP 279 .

How do I access the index in a for loop like the following?

ints = [8, 23, 45, 12, 78]
for i in ints:
    print('item #{} = {}'.format(???, i))

I want to get this output:

item #1 = 8
item #2 = 23
item #3 = 45
item #4 = 12
item #5 = 78

When I loop through it using a for loop, how do I access the loop index, from 1 to 5 in this case?

解决方案

Using an additional state variable, such as an index variable (which you would normally use in languages such as C or PHP), is considered non-pythonic.

The better option is to use the built-in function enumerate(), available in both Python 2 and 3:

for idx, val in enumerate(ints):
    print(idx, val)

Check out PEP 279 for more.

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