if条件测试
cars = ['audi','bmw','subaru','toyota']
for car in cars:
if car =='bmw':
print(car.upper())
else:
print(car.title())
Audi
BMW
Subaru
Toyota
条件测试
- 每条if语句的核心都是一个值为True或False的表达式,这种表达式被称为条件测试
- 如果是True执行if语句后面的代码,如果是False,python就忽略这些代码
检查是否相等
car = 'audi'
car == 'audi'
True
car = 'audi'
car == 'bmw'
False
检查是否相等时不考虑大小写
- 检查是否相等时区分大小写
- 如果大小写无关紧要,只想检查变量的值,可将变量的值转换为小写
car = 'Audi'
car == 'audi'
False
car = 'Audi'
car.lower()=='audi'
True
检查是否不相等
requested_stopping ='mushrooms'
if requested_stopping != 'anchovies':
print("Hold the anvhovies!")
Hold the anvhovies!
比较数字
- 结果True 和 False
- 条件语句中包含各种数字比较,小于、小于等于、大于、大于等于
age = 18
age ==18
True
answer =17
if answer != 42:
print("That is not the correct answer .Please try again!")
That is not the correct answer .Please try again!
age = 19
age < 21
True
检查多个条件
- 1.使用and检查多个条件
- 两个条件都为True,两个条件都通过了,整个表达式为True
- 至少有一个没有通过,整个表达式为False
- 改善可读性,可将每个表达式放在一对括号内
-
- 使用or检查多个条件
- 至少有一个条件满足,整个表达式为True
- 两个条件都没有铜鼓,整个表达式为False
age_1 = 18
age_0 >= 21 and age_1>= 21
False
age_0 = 22
age_1 = 22
(age_0 >= 21) and (age_1>= 21)
True
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中
requested_toppings = ['mushrooms','oninons','pineapple']
'mushrooms' in requested_toppings
True
requested_toppings = ['mushroooms','oninons','pineapple']
'pepperoni' in requested_toppings
False
布尔表达式