python3学习笔记1

谁借莪１个温暖的怀抱￠ 2022-12-27 14:02 240阅读 0赞

一、知识点  
1.声明变量，使用env，而不用pyhon程序路径是因为系统中可能有多个版本的Python

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

2.注释符号

单行用#号，多行注释用三个单引号 ''' 或者三个双引号 """ 将注释括起来

3.格式化输出  
方式一：

#!/usr/bin/env python   
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    username = input("username:")
    age = input("age")
    Job = input("job")
    salary = input("salary")
    info = '''
    ------------info of %s -------
    Name:%s
    Age:%s
    Job:%s
    Salary:%s
    '''%(username,username,age,Job,salary)
    print(info)

方式二：

#!/usr/bin/env python   
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    username = input("username:")
    age = input("age")
    job = input("job")
    salary = input("salary")
    info = '''
    ------------info of {name} -------
    Name:{name}
    Age:{age}
    Job:{job}
    Salary:{salary}
    '''.format(name=username,age=age,job=job,salary=salary)
    print(info)

4.使用getpass模块实现输入密文

#!/usr/bin/env python   
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    import getpass
    username = input("username")
    password = getpass.getpass("password")
    print(username,password)

5.使用if else语句实现简单判断

#!/usr/bin/env python   
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    import getpass
    _username='rrr'
    _password='abc123'
    username = input("username")
    password= input("password")
    if _username==username and _password==password:
        print("Welcome user {name} login...".format(name=username))
    else:
        print("Invalid username or password")

6.小程序猜年龄  
使用if else循环

#!/usr/bin/env python   
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    age_of_oldboy = 56
    guess_age = int(input("guess age"))
    if guess_age == age_of_oldboy :
        print("yes,you got it")
    elif guess_age > age_of_oldboy :
        print("think smaller.")
    else:
        print("think bigger!")

使用while循环，未猜对之前一直循环

#!/usr/bin/env python
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    age_of_oldboy = 56
    while True:
        guess_age = int(input("guess age"))
        if guess_age == age_of_oldboy :
            print("yes,you got it")
            break
        elif guess_age > age_of_oldboy :
            print("think smaller.")
        else:
            print("think bigger!")

设置猜的次数

#!/usr/bin/env python
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    age_of_oldboy = 56
    count=0
    while count < 3:
        guess_age = int(input("guess age"))
        if guess_age == age_of_oldboy :
            print("yes,you got it")
            break
        elif guess_age > age_of_oldboy :
            print("think smaller.")
        else:
            print("think bigger!")
        count = count +1
    else:
        print("you have tried too many times.")

**上面的循环正常走完才运行else，break后不运行else**  
使用for循环

#!/usr/bin/env python
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    age_of_oldboy = 56
    for i in range(3):
        guess_age = int(input("guess age"))
        if guess_age == age_of_oldboy :
            print("yes,you got it")
            break
        elif guess_age > age_of_oldboy :
            print("think smaller.")
        else:
            print("think bigger!")
    else:
        print("you have tried too many times.")

for循环其它用法：  
打印1-10中的数字，每隔2个打印一次

#!/usr/bin/env python   
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    for i in range(1,10,2):
        print("loop",i)

优化程序增加判断

#!/usr/bin/env python
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    age_of_oldboy = 56
    count = 0
    while count < 3:
        guess_age = int(input("guess age"))
        if guess_age == age_of_oldboy :
            print("yes,you got it")
            break
        elif guess_age > age_of_oldboy :
            print("think smaller.")
        else:
            print("think bigger!")
        count +=1
        if count == 3 :
            continue_confirm = input("do you want to keep guessing ?")
            if continue_confirm != 'n' :
                count = 0

**continue关键字作用为跳出本次循环，进入下次循环**

#!/usr/bin/env python   
    # -*- coding:utf-8 -*-
    # Author:yuhuan
    for i in range(0,10):
        if i < 3:
            print("loop")
        else:
            continue
        print("hehe...")

输出结果为：

loop
    hehe...
    loop
    hehe...
    loop
    hehe.