《python编程从入门到实践》if知识点

#if-else语句格式，比如：

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

for car in cars:

    if car=='bmw':

        print(car.upper())

   else:

       print(car.title())

#if-else-if语句格式，比如：

age=66

if age<2:

    print("婴儿！")

elif age<4:

   print("蹒跚学步！")

elif age<13:

   print("儿童！")

elif age<20:

   print("青少年！")

elif age<65:

   print("成年人！")

else:

   print("老年人！")

#使用if检查特殊元素，比如：

requested_toppings=['mushroom','green peppers','extra cheese']

for requested_topping in requested_toppings:

    if requested_topping=='green peppers':

        print("Sorry,we are out of "+requested_topping+" right now.")

   else:

       print("Adding "+requested_topping+".")

#使用if确定列表不是空的，比如：

accounts=[]

if accounts:

   for account in accounts:

        print("Hello " + account + ",thank you for logging in again.")

  else:

       print("We need to find some users!")

#使用if多个列表，比如：

available_toopings=['mushrooms','olives','green peppers','pepperoni','pineapple','extra cheese']

requested_toppings=['mushrooms','french fries','extra cheese']

for requested_topping in requested_toppings:

    if requested_topping in available_toopings:

         print("Adding "+requested_topping+".")

   else:

         print("Sorry,we dont't have "+requested_topping+".")