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 = 182.3 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 default2.5 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 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.")本文参与 腾讯云自媒体分享计划，分享自作者个人站点/博客。
原始发表：2019-06-09 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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