变量、常量、input、if语句

Chapter2 Python基础

2.1 变量命名规则

字母、数字、下划线组成不能数字开头不能使用python中的关键字变量名具有意义推荐驼峰（ArvinGood）、或者下划线方式 (arvin_good) 命名

标准示例：

your_name = 'Jack Ma'

2.2 常量

全部大写的变量名就是常量 ARVIN = 99

示例：

ARVIN_AGE = 18

2.3 注释

三种方式： “#”号单行注释‘’‘三个单引号和三个双引号”“”进行多行注释

例：

# The idle boy is almost invariably poor and anxious. 单行注释 ''' 这是多行注释示范 ''' """ 多行注释示范 """

2.4 输入输出

用户输入 input 注意：input获取到的内容都是字符串类型用户输出 print print打印出内容 your_id = input("input your id identifier: ") your_pwd = input("input your password: ") print("Your id is {}, Your password is {}".format(your_id, your_pwd)) 运行结果： input your id identifier: Jack input your password: default Your id is Jack, Your password is default

2.5 五种if条件判断语句

单if条件判断

if 条件： #条件判断 > < ==

​ print(‘真实’) #条件成立则执行

if 10 > 8: print("You are right.")

if else条件判断

if 10 > 20: print("10 is bigger than 2.") else: print("10 is smaller than 2.")

if elif elif else 条件判断

a = "jack" if 10 > 50: print("10 is bigger than 5.") elif type(a) == "str": print("a is a string.") elif 20 == 20: print("20 is equal 20.") else: print("All of them are false.") 运行结果： 20 is equal 20.

多个同级if语句

a = "jack" if 10 == 20: print("10 is equal 20.") if a == "jack": print(a ,"is the same as jack.") if 10 == 10: print("10 is equal 10.") 运行结果： jack is the same as jack. 10 is equal 10.

if与if语句之间的嵌套

id = int(input("input your id number: ")) pwd = input("input your passwrd: ") if id == 9: print("GO ON.") if pwd == "default": print("You logged in successfully.") else: print("Your password is incorrect.") else: print("Your id was typed incorrectly.")

转载于:https://www.cnblogs.com/Tao9/p/10969101.html

相关资源：JAVA上百实例源码以及开源项目