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作者:动漫动画

The worlds can be one together
Cosmos without hatred
Stars like diamonds in your eyes
The ground can be space space space space space
With feet marching towards a peaceful sky
All the Moonmen want things their way
But we make sure they see the sun
Good bye Moonmen
You said good bye Moonmen
Good bye Moonmen
澳门新葡8455最新网站:循环语句。Good bye Moonmen

Python While 循环语句

By a lake,  two hamsters lived there, mother and son. One day, the little hamster said to his mother, ‘Mom, I’d like to travel around the lake a week.’

------ a song about genocide of all carbon matter

Python 编程中 while 语句用于循环执行程序,即在某条件下,循环执行某段程序,以处理需要重复处理的相同任务。其基本形式为:while 判断条件:

‘great!’ The mother hamster said, ‘well, have a nice trip.’

执行语句……

‘See you, mum.’ The little hamster went off on a trip.

执行语句可以是单个语句或语句块。判断条件可以是任何表达式,任何非零、或非空的值均为true。

After walking  for a while he saw an old turtle.

当判断条件假false时,循环结束。

‘Grandpa tortoise, where are you going?’ Asked the little hamster.

执行流程图如下:

‘Oh, little hamster, I'm going to the river below the hill to see my grandson.’ The old turtle said kindly, and he paused, then said, ‘but I am too slow, I am afraid I could not arrive on time.’

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The little hamster had a brainwave and said, ‘you can retract your head and feet inside your shell. I'll push you, and you'll be there soon.’

Gif 演示 Python while 语句执行过程

‘That would be great’ the old turtle said slowly. ‘Thank you, the young man!’

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So the little hamster pushed it and the old turtle rolled down. ‘Good bye.’

复杂一点:

‘Good bye.’ As soon as they waved goodbye, hamster suddenly slipped and fell into the water.

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‘Help!......’ The little hamster only saw a shadow and was carried to its back, then he passed out......

实例

It was second days when he woke up, he suddenly found the goldfish beside the lake. ‘did you save me?’ Said the little hamster.

#!/usr/bin/python

"Yes," answered the goldfish, ‘how did you fall into the lake?’

count = 0

‘I slipped, and I plan to travel around the lake for a week," said the little hamster.

while (count < 9):

The goldfish said, ’Really? I can carry you. Jump on my back.’

print 'The count is:', count

‘It’s amazing! thanks!’ said the little hamster.

count = count 1

In this way, the little hamster continued its journey.

print "Good bye!"

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运行实例 »

以上代码执行输出结果:The count is: 0

The count is: 1

The count is: 2

The count is: 3

The count is: 4

The count is: 5

The count is: 6

The count is: 7

The count is: 8

Good bye!

while 语句时还有另外两个重要的命令 continue,break 来跳过循环,continue 用于跳过该次循环,break 则是用于退出循环,此外"判断条件"还可以是个常值,表示循环必定成立,具体用法如下:

# continue 和 break 用法

i = 1

while i

0: # 非双数时跳过输出

continue

print i # 输出双数2、4、6、8、10

i = 1

while 1: # 循环条件为1必定成立

print i # 输出1~10

i = 1

if i > 10: # 当i大于10时跳出循环

break

无限循环

如果条件判断语句永远为 true,循环将会无限的执行下去,如下实例:

实例

#!/usr/bin/python

# -*- coding: UTF-8 -*-

var = 1

while var == 1 : # 该条件永远为true,循环将无限执行下去

num = raw_input("Enter a number :")

print "You entered: ", num

print "Good bye!"

以上实例输出结果:Enter a number :20

You entered: 20

Enter a number :29

You entered: 29

Enter a number :3

You entered: 3

Enter a number between :Traceback (most recent call last):

File "test.py", line 5, in <module>

num = raw_input("Enter a number :")

KeyboardInterrupt

注意:以上的无限循环你可以使用 CTRL C 来中断循环。

循环使用 else 语句

在 python 中,while … else 在循环条件为 false 时执行 else 语句块:

实例

#!/usr/bin/python

count = 0

while count < 5:

print count, " is less than 5"

count = count 1

else:

print count, " is not less than 5"

以上实例输出结果为:0 is less than 5

1 is less than 5

2 is less than 5

3 is less than 5

4 is less than 5

5 is not less than 5

简单语句组

类似 if 语句的语法,如果你的 while 循环体中只有一条语句,你可以将该语句与while写在同一行中, 如下所示:

实例

#!/usr/bin/python

flag = 1

while : print 'Given flag is really true!'

print "Good bye!"

注意:以上的无限循环你可以使用 CTRL C 来中断循环。

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