if-else和while循环

用户登陆验证： if-else 判断

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

import getpass

passwd='
name='sunhao'

user_name=input('请输入用户名：')
user_passwd=getpass.getpass('请输入你的密码：')

if user_name==name and user_passwd==passswd:    print('Welcome user {_name} login.'.format(_name=user_name))else:    print('Invalid username or password')

getpass模块在pycharm中不能用

 

猜年龄：  while 循环

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author:sun_96

age_of_me=26

count=0
#猜年龄最多只让猜5次

while count<5:      

    guess_age=int(input('请输入要猜的年龄：'))

    if guess_age == age_of_me:
        print('恭喜你，猜对了！')
    elif guess_age < age_of_me:
        print("smaller")
    else:
        print('bigger')

    count+=1
    if count ==5:
        continue_guess=input('是否继续：请输入yes  or no')
        if continue_guess == 'yes':
            count=0

else:
    print("密码多次输错")

猜年龄：  for 循环

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#Author:sun_96

age_of_me=26

count=0
#猜年龄最多只让猜5次

for i in range(10):      

    guess_age=int(input('请输入要猜的年龄：'))

    if guess_age == age_of_me:
        print('恭喜你，猜对了！')
    elif guess_age < age_of_me:
        print("smaller")
    else:
        print('bigger')

else:
    print("密码多次输错")

表达式for loop

最简单的循环10次

 #_*_coding:utf-8_*_
 __author__ = 'sunhao'

 for  i  in range(10)：

 print(i)

输入：

loop 0
loop 1
loop 2
loop 3
loop 4
loop 5
loop 6
loop 7
loop 8
loop 9

break 和 continue

for i in range(10):
    if i > 5:
        print('Break!')
        break  #跳出整个循环  结束整个循环
    print(i)
 

输出：

0
1
2
3
4
5
6
Break!

for i in range(10):
    if i < 5:
        print('Continue')
        continue  #只是跳出本次循环    print(i)输出：

continue!
continue!
continue!
continue!
continue!
5
6
7
8
9