【python之路4】循环语句之while

 

 

补充:

n = 1
while n<=10:
    print(n)
    n += 1
else:
    print("进入else")  #else语句会执行，条件不满足进入else



n = 1
while n<=10:
    print(n)
    n += 1
    if n==5:
        break
else:
    print("进入else")  #else语句不执行，因为是通过break退出的循环，没有经过条件判断，所以不会出现条件不满足的情况

 for i in s:

　　print(i)

else:

　　print("结束")

for循环同样可以带else，同样的自然结束循环时执行，如果是break退出的循环也不会执行else后面的语句

 

 

1、while 循环语句

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import time
bol = True
while bol:
    print '1'
    time.sleep(1)
    bol = False

print 'hello,world!'

2、无限的输出数字

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import time
n = 0
while True:
    n = n + 1
    time.sleep(1)
    print n

3、打印输出10个数字

#!/usr/bin/env python
# -*- coding:utf-8 -*-
bol = True
n = 0
while bol:
	n = n + 1
	if n == 10:
		bol = False
	print n
print "end"

 4、break跳出当前循环语句继续向下运行

#!/usr/bin/env python
# -*- coding:utf-8 -*-
n = 0
while True:
	n = n + 1
	print n
	if n == 10:
		break

print "end"

 5、continue退出本次循环，继续下次循环，循环输出1,2,3,4,5,6,8,9,10

#!/usr/bin/env python
# -*- coding:utf-8 -*-
i = 0
while i < 10:
	i += 1
	if i == 7:
		continue
	print i

#!/usr/bin/env python
# -*- coding:utf-8 -*-
n = 0
while True:
	n += 1
	if n == 7:
		n += 1
		continue
	print n
	if n == 10:
		break

#!/usr/bin/env python
# -*- coding:utf-8 -*-
i = 1
while i <= 10:
	if i != 7:
		print i
	i += 1

 6、求1-100的和

#!/usr/bin/env python
# -*- coding:utf-8 -*-
i = 1
sum = 0
while True:
	sum += i
	if i == 100:
		break
	i += 1
print sum

 7、输出 1-100 内的所有奇数

#!/usr/bin/env python
# -*- coding:utf-8 -*-

#输出 1-100 内的所有奇数
i = 1
while True:
	if i % 2 == 1:
		print i
	if i == 100:
		break
	i += 1

8、输出 1-100 内的所有偶数

#!/usr/bin/env python
# -*- coding:utf-8 -*-

#输出 1-100 内的所有偶数
i = 1
while True:
	if i % 2 == 0:
		print i
	if i == 100:
		break
	i += 1

9、求1-2+3-4+5 ... 99的所有数的和

#!/usr/bin/env python
# -*- coding:utf-8 -*-

#求1-2+3-4+5 ... 99的所有数的和
i = 1
sum = 0
while True:
	if i % 2 == 1:
		sum += i
	elif i % 2 == 0:
		sum -= i
	if i == 100:
		break
	i += 1
print sum

10、用户登陆（三次机会重试）

#!/usr/bin/env python
# -*- coding:utf-8 -*-

#用户登陆（三次机会重试）
n = 0
while True:
	psw = raw_input("Enter Password:")
	if psw != '123456':
		print "Sorry,Error Password!"
		n = n + 1
		if n == 3:
			print "you try 3 times,the programe is over!"
			break
	else:
		print "Congratulations!Password is right!"
		break
	

　　

#!/usr/bin/env python# -*- coding:utf-8 -*-
#输出 1-100 内的所有奇数i = 1while True:if i % 2 == 1:print iif i == 100:breaki += 1