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python裡while先print是為什麼_初識python07--使用者輸入和while循環

7.1、函數input()

用int()将輸入轉換成整型

求模運算符:%,用于兩數相除傳回餘數。eg. 100%10=0

練習:

# coding=GBK

#7-1

car=input('What car do you wanna rent?')

print('Let me see if I can find you a Subaru' )

#7-2

people=input('How many peole eat?')

people=int(people)

if people > 8:

print('There is no empty table.')

else:

print('Free table')

#7-3

number=input('Enter a number,and I will tell if it is a multiple of 10 ')

number=int(number)

if number%10 == 0:

print('It is a multiple of 10')

else:

print("It isn't")

7.2 while 循環

while循環不斷運作。當指定條件不滿足時,退出循環。

使用标志用于判斷程式是否處于活動狀态。True運作,False結束。

用break退出循環。

用continue結束此次循環,進入下次循環。

務必對每個While循環進行測試,以免進入無限循環。當進入無限循環時,按Ctrl+C退出或關閉視窗。

相關練習

#7-4

print('Please add your ingredient: ')

a=''

while a != 'quit':

a=input()

if a != 'quit':

print('We will add '+a)

else:

print('Please wait a minute')

#7-5 and 7-6

prompt='Please enter your age: '

prompt+='\ninput quit to exit.'

active=True

while active:

age=input(prompt)

if age=='quit':

break

else:

if int(age) < 3:

print('Free')

elif int(age) <= 12:

print('Please pay $10.')

else:

print('Please pay $15.')

7.3 用while處理清單和字典

在清單間移動元素:

練習:

#7-8、7-9

解一:

sandwich_orders=['A','pastrami','C','pastrami','E','pastrami']

print('Pastrami is sold out')

finished_sandwich=[]

b=0

while b < len(sandwich_orders):

a=sandwich_orders[b]

if a.lower() == 'pastrami':

b=b+1

continue

else:

finished_sandwich.append(a)

print('I made your '+a)

b=b+1

print(finished_sandwich)

删除清單内的特定值:

#7-9

sandwich_orders=['A','pastrami','C','pastrami','E','pastrami']

print('Pastrami is sold out')

finished_sandwich=[]

while 'pastrami' in sandwich_orders:

sandwich_orders.remove('pastrami')

finished_sandwich=sandwich_orders

print(finished_sandwich)

使用使用者輸入填充字典:

7-10

#coding=GBK

places={}

active=True

while active:

name=input('姓名:')

place=input('夢想的度假勝地:')

places[name]=place

repeat=input('還有人要回答嗎?(yes/no)')

if repeat.lower() =='no':

active=False

print('調查結果')

for name,place in places.items():

print(name+'想去'+place+'.')