python基础之条件语句

检查相等和不等

多个检查条件

age1 = 22
age2 = 19
s1 = age1 > 21 and age2 > 19
print(s1)
s2 = age1 > 21 or age2 > 19
print(s2)

检查是否包含在列表内

requested_toppings = ['mushrooms','onions','pineapple']
s1 = 'mushrooms' in requested_toppings
print(s1)
s2 = 'pepperoni' in requested_toppings
print(s2)

检查不包含

requested_toppings = ['mushrooms','onions','pineapple']
s1 = 'mushrooms' not in requested_toppings
print(s1)
s2 = 'pepperoni' not in requested_toppings
print(s2)

if语句

age = 19
if age >= 18:
	print('You are old enough to vote')
if age >= 20:
	print('is no print')

if-elif-else语句

age = 12
if age < 4:
	price = 0
elif age < 18:
	price = 5
elif age < 65:
	price = 10
else:
	price = 5
print('Your admission cost is $' + str(price) + '.')

检查特殊元素

requested_toppings= ['mushrooms','green peppers','extra cheese']
for requested_topping in requested_toppings:
	if requested_topping == 'green peppers':
		print('Sorry,we are out of green peppers right now')
	else:
		print('Adding' + requested_topping + '.')

requested_toppings= []
if requested_toppings:
	for requested_topping in requested_toppings:
		print('Adding ' + requested_topping + '.')
else:
	print('Are you sure you want a plain pizza?')

available_toppings = ['mushrooms','olives','green peppers','pepperoni']
requested_toppings= ['mushrooms','french fries','green peppers']
for requested_topping in requested_toppings:
	if requested_topping in available_toppings:
		print('Adding ' + requested_topping + '.')
	else:
		print("Sorry,we don\'t have " + requested_topping + '.')