模擬現(xiàn)實世界中的情形
大多數(shù)程序都旨在解決最終用戶的問題
第5章 ?if語句
條件測試
特定值是否包含在列表中 in
5.3 if-elif-else結(jié)構(gòu)
如果你只想執(zhí)行一個代碼塊溉奕，就使用if-elif-else結(jié)構(gòu)熙侍，如果要運行多個代碼塊吁朦，就使用一系列獨立的if語句柒室。
動手試一試：
#5-3 外星人顏色#1
alien_color='green'
if alien_color=='green':
? ? print('This player got 5 points!')
alien_color='red'
if alien_color=='green':
? ? print('This player got 5 points!')
#2? ?
alien_color='green'
if alien_color=='green':
? ? print('This player got 5 points!')
else:
? ? print('This player got 10 points!')
alien_color='yellow'
if alien_color=='green':
? ? print('This player got 5 points!')
else:
? ? print('This player got 10 points!')?
#3? ?
alien_color='green'
if alien_color=='green':
? ? print('This player got 5 points!')
elif alien_color=='yellow':
? ? print('This player got 10 points!')
else:
? ? print('This player got 15 points!')
alien_color='yellow'
if alien_color=='green':
? ? print('This player got 5 points!')
elif alien_color=='yellow':
? ? print('This player got 10 points!')
else:
? ? print('This player got 15 points!')
alien_color='green'
if alien_color=='red':
? ? print('This player got 5 points!')
elif alien_color=='yellow':
? ? print('This player got 10 points!')
else:
? ? print('This player got 15 points!')? ?
age=32
if age<2:
? ? print('He is a baby!')
elif age>=2 and age<4:
? ? print('He is toddling!')
elif age>=4 and age<13:
? ? print('He is a child!')
elif age>=13 and age<20:
? ? print('He is a teenager!')
elif age>=20 and age<65:
? ? print('He is an adult!')
else:
? ? print('He is an aged man!')
favorite_fruits=['orange','cherry','watermelon']
if 'orange' in favorite_fruits:
? ? print("You really like orange!")
if 'cherry' in favorite_fruits:
? ? print("You really like cherry!")
if 'apple' in favorite_fruits:
? ? print("You really like apple!")
if 'pear' in favorite_fruits:
? ? print("You really like pear!")
if 'watermelon' in favorite_fruits:
? ? print("You really like watermelon!")
5.4 使用if語句處理列表
確定列表不是空的 ?if requested_toppings:
動手試一試：
#5-8 以特殊方式跟管理員打招呼
users=['admin','bing','yang','ling','fei']
for user in users:
? ? if user=='admin':
? ? ? ? print('Hello admin,would you like to see a status report?')
? ? else:
? ? ? ? print('Hello '+user.title()+",thank you for logging in again!")
users=[]
if? users:
? ? for user in users:
? ? ? ? if user=='admin':
? ? ? ? ? ? print('Hello admin,would you like to see a status report?')? ? ? ?
? ? ? ? else:
? ? ? ? ? ? print('Hello '+user.title()+",thank you for logging in again!")
else:
? ? print('We need to find some users!')
current_users=['admin','bing','yang','ling','fei']?
new_users=['wang','Bing','Yang','wen','ma']? ?
for new_user in new_users:
? ? ? ? if new_user.lower()? not in current_users:
? ? ? ? ? ? print(new_user.lower()+',This user is available!')
? ? ? ? else:
? ? ? ? ? ? print(new_user.lower()+',This user is forbidden!')
sequences=list(range(1,10))
for sequence in sequences:
? ? if sequence<=3 :
? ? ? ? if sequence==1 :
? ? ? ? ? ? print('1st')
? ? ? ? if sequence==2 :
? ? ? ? ? ? print('2nd')
? ? ? ? if sequence==3 :
? ? ? ? ? ? print('3rd')? ? ? ? ? ? ? ? ?
? ? else:? ?
? ? ? ? print(str(sequence)+'th')
第6章 字典
鍵值對
alien_0={}
alien_0['color']='green'
刪除鍵值對
del alien_0['points']
動手試一試：
# 6-1 人
people={
? ? ? ? 'first_name':'xia',
? ? ? ? 'last_name':'wang',
? ? ? ? 'age':32,
? ? ? ? 'city':'beijing'
? ? ? ? }
print(people['first_name'])
print(people['last_name'])
print(people['age'])
print(people['city'])
print('first_name\n\t'+people['first_name'])
1、遍歷字典
for key,value in user_0.items():
for name in favorite_language.keys(): ?等價于for name in favorite_language：
for language in favorite_language.values():
集合類似于列表逗宜，但每個元素都必須是獨一無二的
for language in set(favorite_language.values()):
嵌套
1雄右、在列表中存儲字典
for alien_number in range(0,30):
new_alien={}
aliens.append(new_alien)
# 字典列表
aliens=[]
for alien_number in range(0,30):
? ? new_alien={'color':'green','points':5,'speed':'slow'}
? ? aliens.append(new_alien)
for alien in aliens[0:3]:
? ? if alien['color']=='green':
? ? ? ? alien['color']='yellow'
? ? ? ? alien['speed']='medium'
? ? ? ? alien['points']=10
? ? elif alien['color']=='yellow':
? ? ? ? alien['color']='red'
? ? ? ? alien['speed']='fast'
? ? ? ? alien['points']=15
for alien in aliens:
? ? print(alien)
2、在字典中存儲列表
# 2纺讲、在字典中存儲列表
favorite_languages={
? ? ? ? 'jen':['python','ruby'],
? ? ? ? 'sarah':['c'],
? ? ? ? 'edward':['ruby','go'],
? ? ? ? 'phil':['python','haskell']
? ? ? ? }
for name,languages in favorite_languages.items():
? ? if len(languages)>1:
? ? ? ? print(name.title()+"'s favorite languages are:")
? ? else:
? ? ? ? print(name.title()+"'s favorite language is:")
? ? for language in languages:
? ? ? ? print("\t"+language.title())
3擂仍、在字典中存儲字典
