Python编程：从入门到实践-if 语句

• 简单示例

#!/usr/bin/env python
#-*- encoding:utf-8 -*-
cars = ['audi', 'bmw', 'subaru', 'toyota']
for car in cars:
  if car == 'bmw':
    print(car.upper())
  else:
    print(car.title())

C:\PyProjects>C:/Python37/python3.exe c:/PyProjects/demo.py
Audi
BMW
Subaru
Toyota

• 条件测试

• 检查是否相等

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>>> car = 'bmw' >>> car == 'bmw' True >>> car = 'audi' >>> car == 'bmw' False >>>

•  检查是否相等时不考虑大小写

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>>> car = 'Audi' >>> car == 'audi' False >>> car = 'Audi' >>> car.lower() == 'audi' True

• 检查是否不相等

requested_toppings = 'mushrooms'
if requested_toppings != 'anchovies':
  print("Hold the anchovies!")

• 比较数字

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>>> age = 18 >>> age == 18 True

 

+ View Code?

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#!/usr/bin/env python #-*- encoding:utf-8 -*- answer = 17 if answer != 42:   print("That is not the correct answer.Please try again!")

　

+ View Code?

1 2	C:\PyProjects>C:/Python37/python3.exe c:/PyProjects/demo.py That is not the correct answer.Please try again!

•  检查多个条件

使用and检查多个条件

+ View Code?

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>>> age_0 = 22 >>> age_1 = 18 >>> age_0 >= 21 and age_1 >=21 False >>> age_1 = 22 >>> age_0 >= 21 and age_1 >=21 True

　使用or检查多个条件

+ View Code?

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>>> age_0 = 22 >>> age_1 = 18 >>> age_0 >= 21 or age_1 >= 21 True >>> age_0 = 18 >>> age_0 >= 21 or age_1 >= 21 False

• 检查特定值是否包含在列表

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>>> requested_toppings = ['mushrooms', 'onions', 'pineapple'] >>> 'mushrooms' in requested_toppings True >>> 'pepperoni' in requested_toppings False >>>