Python第四章 ：字典操作

#if 条件语句
cars = ['bmw','audi','subaru','toyota']

for car in cars:
    if car == 'bmw':#检查是否相等时考虑大小写
        print(car.upper())
    else:
        print(car.title())
mycar = 'benci'
if mycar not in cars:
    print(mycar.title() + ", you can post a response if  you wish.")
#if-else条件语句

requested_toppings =[]
if requested_toppings:
    for  requested_topping in  requested_toppings:
        print("adding")
else:
        print("are you sure you want a plain pizza?")
#字典:键-值对
alien_0 ={'color': 'green','point': 5}
print(alien_0['color'])
print(alien_0['point'])
print(alien_0)
#添加键-对值
alien_0['x_position'] = 0
alien_0['y_position'] = 25
print(alien_0)
#写字典
alien_0 ={}
alien_0['color'] = 'green'
alien_0['points'] = 5
print(alien_0)
#改字典
alien_0 ={'color': 'green'}
print("the alien is "+ alien_0['color'] +".")
alien_0['color']='yellow'
print("the alien is now"+ alien_0['color'] +".")
#改字典中的值
alien_0={'x_position': 0, 'y_position': 25, 'speed': 'medium'}
print("Orginal x-position: " +str(alien_0['x_position']))

if alien_0['speed'] == 'slow':
    x_increment =1
elif alien_0['speed'] =='medium':
    x_increment=2
else:
    x_increment = 3
alien_0['x_position'] = alien_0['x_position'] + x_increment

print("New x-position: "+ str(alien_0['x_position']) )
#删除键值对
del alien_0['speed']
print(alien_0)
#由类对象组成字典
favorite_languages ={
    'jen': 'python',
    'sarah': 'C',
    'edward':'ruby',
    'phil':'python',
     }
print("Sarah's favorite language is" + favorite_languages['sarah'].title() +".")
for name, language in favorite_languages.items():
    print(name.title() + "'s favorite language is " + language.title() + ".")
#如何遍历字典
user_0={
    'username': 'efermi',
    'first': 'enrico',
    'last': 'fermi',
    }
for key,Value in user_0.items():
    print("\nKey " + key)
    print("Value: " + Value)
for key in user_0:
    print(key.title())
for key in user_0.keys():
    print(key.title())
for language in user_0.values():
    print(language.title())