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python關於for循環的幾個函數

for ... in ...

//?for?...?in?字符串

for?i?in?'abc':

print(i)

'''

a

b

c

'''

//?for?...?in?數組

for?i?in?['a',?'b',?'c']:

print(i)

'''

a

b

c

'''

//?for?...?in?元組

for?i?in?('a',?'b',?'c'):

print(i)

'''

a

b

c

'''

//?for?...?in?字典(得到的是字典的key)

for?k?in?{'學號':30,'姓名':'小明'}:

print(k)

'''

姓名

學號

'''

//?for?...?in?字典.items()(得到的是字典的key,?value)

for?k,?v?in?{'學號':30,'姓名':'小明'}.items():

print(k,?v)

'''

姓名?小明

學號?30

'''

for ... in range(...)

//?for?...?in?range(num)

for?i?in?range(3):

print(i)

'''

0

1

2

'''

//?for?...?in?range(num1,?num2)

for?i?in?range(1,?3):

print(i)

'''

1

2

'''

//?for?...?in?range(num1,?num2,?num3)

for?i?in?range(3,?1,?-1):

print(i)

'''

3

2

'''

for?i?in?range(1,?5,?2):

print(i)

'''

1

3

'''

倒敘

for?i?in?reversed([1,2,3,4]):

print(i)

’‘’

4

3

2

1

‘’‘

又想得到遍歷次數,又想得到數組值

for i,e in enumerate(array):

for?i,e?in?enumerate(['21dw',?55,?22,?'rw']):

print(i,?e)

'''

0?21dw

1?55

2?22

3?rw

'''

列表生成式

[...for ... in array]]

print([x?*?x?for?x?in?[2,?34,?324,?43]])

'''

[4,?1156,?104976,?1849]

'''

//相當於

list?=?[]

for?x?in?[2,?34,?324,?43]:

list.append(x?*?x)

print(list)