题目：

思考循环结构，看看它是怎样运行的，对我们认识程序有何益处。

知识点：

list, for-loop, range

练习代码：

练习1

the_count = [1, 2, 3, 4, 5]

# this first kind of for-loop goes through a list
for number in the_count:
    print('This is count %d' % number)

结果：

This is count 1
This is count 2
This is count 3
This is count 4
This is count 5

练习2

fruits = ['apples', 'oranges', 'pears', 'apricots']

for fruit in fruits:
    print('A fruit of type: %s' % fruit)

结果：

A fruit of type: apples
A fruit of type: oranges
A fruit of type: pears
A fruit of type: apricots

练习3

change = [1, 'pennies', 2, 'dimes', 3, 'quarters']
for i in change:
    print('I got %r' % i)
# notice we have to use %r since we don't know what's in it.

结果：

I got 1
I got 'pennies'
I got 2
I got 'dimes'
I got 3
I got 'quarters'

 

练习4

elements = []
for i in range(0, 6):
    print('Adding %d to the list.' % i)
    elements.append(i)

结果：

Adding 0 to the list.
Adding 1 to the list.
Adding 2 to the list.
Adding 3 to the list.
Adding 4 to the list.
Adding 5 to the list.

for i in elements:
    print('Element was: %d' % i)

结果：

Element was: 0
Element was: 1
Element was: 2
Element was: 3
Element was: 4
Element was: 5

来自《笨办法学Python》