python學習中…
《a byte of python 3》學習摘要
chapter 7 控制流
7.1 if語句
number = 20
guess = int(input('enter an integer ='))
if guess == number:
print('congratulations!')
print('(沒錢)')
elif guess > number:
print('it is higher')
else:
print('it is lower')
print('done')
輸出
>>>
enter an integer =15
it is lower
done
>>> ******************************== restart ******************************==
>>>
enter an integer =80
it is higher
done
>>> ******************************== restart ******************************==
>>>
enter an integer =20
congratulations!
(沒錢)
done
elif 從句,它事實上把兩個相關聯的if else-if else 語句合併為乙個if-elif-else 語句。這使得程式更加簡單,並且減少了所需的縮排數量。
注:if else elif 後面都要跟有冒號。
7.2 while語句
number = 32
running = true
while running:
guess = int(input('enter an integer ='))
if guess == number:
print('you win')
running = false
elif guess < number:
print('lower')
else:
print('higher')
else:
print('the loop is over')
print('done')
輸出
enter an
integer =98
higher
enter an
integer =88
higher
enter an
integer =1
lower
enter an
integer =32
you win
the loop is over
done
7.3 for迴圈
for i in range(1, 10):
print(i)
else:
print('over')
輸出
>>> 12
3456
789over
range(1,5) 給出序列[1, 2, 3, 4]。預設地, range 的步長
為1。如果為range 提供第三個數,那麼它將成為步長。
for i in range(1, 10, 3):
print(i)
else:
print('over')
輸出
>>> 14
7over
>>>
7.4 break語句
while
true:
s = input('enter something:')
if s == 'quit':
break
else:
print('the length is:',len(s))
print('done')
輸出
enter something:my
name
is anna
the length
is: 15
enter something:quit
done
7.5 continue語句
while
true:
s = input("enter something =")
if s == 'quit':
print('the loop is over')
break
if len(s) < 5:
print('it is too short')
continue
print('it is enough')
輸出
>>>
enter something =hello liner
it is enough
enter something =as
it is too short
enter something =quit
the loop is over
>>>
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