python-第01章02章节-密文，if else判断和while，for循环

1，编写用户名及密码然后加密

import getpass
username = input("username")
password = getpass.getpass("password")
print(username,password)

 变秘文需要有模块，调用标准库（import中有的，不需要安装的库，叫做标准库）

import getpass，可以将明文变成密文

import getpass
username = input("username")
password = getpass.getpass("password")
print(username,password)

2. 想要判断用户名和密码对不对，所以我们需要判断

username_ = "han"
password_ =  "123"
username = input("username:")
password = input("password:")
print(username,password)

if username_ == username and password_ == password:
    print("welcome  login...")
else:
    print("密码或者用户名错误.")

 python中没有分隔符，所以有相应的强制缩进，省的结束语。如果总显示错误，写的代码没问题，一定要检查缩进问题。

3.判断年龄的大小

age_ = 30
age = int(input("Enter your age:"))
if age == age_:
    print("you are right!")
elif age_ < age:
    print("It is high")
else :
    print("It is low!")

 在python中 if-eiif-lese的循环结构较为简单，在循环体中记得要加“：”

 4.while 循环

判断年龄想要加功能，让其可以猜想三次

while True:
    if count == 3:
        break
    age_ =30
    age = int(input("Enter your age:"))
    if age == age_:
        print("you are right!")
        break
    elif age_ < age:
        print("It is high")
    else:
        print("It is low!")

    count += 

 优化一下：

count = 0
while count < 3:
    age_ =30
    age = int(input("Enter your age:"))
    if age == age_:
        print("you are right!")
        break
    elif age_ < age:
        print("It is high")
    else:
        print("It is low!")

    count += 1
if count == 3：#else：
print("你打印了太多次，请重新登陆！")

 5.for循环

for i in range(10):
    print("loop",i)

 想要跳一个打印一个

for i in range(0，10，2):
    print("loop",i)

将while循环改为for循环

for i in range(3):
    age_ =30
    age = int(input("Enter your age:"))
    if age == age_:
        print("you are right!")
        break
    elif age_ < age:
        print("It is high")
    else:
        print("It is low!")

 range（）的用法见python的函数随笔