PYTHON第三天，,PYTHON之路七、

PYTHON之路

七、基本的if判断

最简单的流程处理：if ...else

If简单练习：

#!/usr/bin/env python

# -*-coding:utf-8 -*-

#if 基本表达式

#用户登录验证

#提示输入用户名和密码

#验证用户名和密码

#如果错误，则输出用户名或密码错误；

#如果成功，则输出欢迎,XXX！

user = ‘zhang‘

password = ‘123.com‘

username = input("username:")

password = input("password:")

if user == username:

print("用户名输入正确") {下层代码}

下层代码：

这个代码的运行要依赖于上一层代码，也就是说上一层代码必须为真（成立），才会读下层代码。///可以理解为上一层的子代码

子代码不能顶行写，否则Python认为是不相关的代码，将会独立执行

Python的默认开发规范：子代码空4格

If ...else语句练习：

#!/usr/bin/env python

# -*-coding:utf-8 -*-

user = ‘zhangjianghua‘

passwd = ‘123.com‘

username = input("username:")

password = input("password:")

if user == username :

print("username is correct...")

if password == passwd:

print("welcome login...")

else:

print("password is invalid...")

else:

print("连用户名都没蒙对，滚粗。。。")

If...else V2 优化版：

#!/usr/bin/env python

#-*-coding:utf-8 -*-

user = "zhangjianghua"

passwd = "123.com"

username = input("username:")

password = input("password:")

ifuser == usernameandpasswd == password:

print("welcome login")

else:

print("Invalid username or password....")

八、猜年龄游戏

（猜年龄游戏V1，猜对即退出）

#!/usr/bin/env python

#-*-coding:utf-8 -*-

age = 19

guess_num = int (input("input your guess num:"))

if guess_num ==age:

print("Congratulations! you got it.")

elif guess_num >age:

print("Think smaller!")

else:

print("Think Big...")

九、for循环

for i in range(10):

print(i)

i 每循环一次i 就会增加1

(猜年龄游戏V2，最大次数三次)

#!/usr/bin/env python

#-*-coding:utf-8 -*-

age = 19

for i in range(10):

if i <3:

guess_num = int(input("input your guess num:"))

if guess_num ==age :

print("恭喜你猜对了")

break #猜对即停止，不往后走了，跳出整个loop

elif guess_num >age:

print("往小了想！")

else:

print("往大了想！")

else:

print("尝试了太多次..拜拜~~")

break

（猜年龄游戏V3，最大循环10次，每3次重新循环）

#!/usr/bin/env python

#-*-coding:utf-8 -*-

#Author: ZhangJiangHua

age = 19

counter =0

for i in range(10):

print(‘--counter:‘,counter)

if counter <3:

guess_num = int(input("input your guess num:"))

if guess_num == age :

print("恭喜你，猜对了！")

break #不往后走了，跳出整个循环

elif guess_num >age:

print("往小了猜！")

else:

print("往大了猜！")

else:

continue_confirm = input("还要继续吗？y|n")

if continue_confirm == ‘y‘:

counter = 0

continue #(跳出当次循环，而不是整个)

else:

print("bye")

break

counter +=1 #counter = counter +1

PYTHON第三天