python入门-IF语句

1 格式

cars = ['audi','bmw','subaru','toyata']

for car in cars:
    if car =='bmw':
        print(car.upper())
    else:
        print(car.title())

python检查相等的时候区分大小写

2 检查是否相等

car='bmw'
car=='bmw'

检查不相等

requested_topping='mushrooms'

if requested_topping !='anchovies':
    print('hold the anchovies!')

3 多个条件 and  or

age_0=22
age_1=18

if age_0>=21 and age_1>=21:
    print('ok')
else:
    print('not ok')

4 检查特定的值 是否在列表中  in   not in

requested_toppings=['mushrooms','onions','pineapple']

'mushrooms' in requested_toppings

'mushrooms' not in requested_toppings

5 IF语句

if condition:

　　do somthing

age=19
if age>=18:
    print('is ok')
    print('this is second ok')

6 if-else语句

age=17
if age>=18:
    print('first is ok')
    print('second is ok')
else:
    print('third is ok')
    print('fourth is ok')

7 if-elif-else 结构

age=12
if age<4:
    print('your admission cost is $0')
elif age<18:
    print('your admission cost is #5')
else:
    print('your adminssion cost is #10')

8 多个elif语句

age=12
if age<4:
    price=0
elif age<18:
    price=5
elif age<65:
    price=10
else:
    price=5

print(price)

9 确认列表是不是空的

requested_toppings=[]
if requested_toppings:
    for requested_topping in requested_toppings:
        print('adding'+requested_topping+".")
    print("
 finished making your pizza!")
else:
    print('are you sure you want a plain pizza')

10 IF语句格式

在  ==  >= <= 两边各加一个空格