python 武浩杰 20210120

'''

遞歸函數(shù)

'''

n = int(input('請輸入n的值：'))

s = list(range(1,n+1))

n = len(s)

a = 1

while n>1:

    a = a*s[n -1]

    n = n - 1

print('a=%d'%a)

'''

def factorail(n):

    s = 1

    for i in range(1,n+1):

        s *= i

    return s

print(factorail(5))

阿飛

'''

n! = (n-1)!*n

(n-1)! = (n-2)!*n

...

2! = (2-1)!*2

1! = 1

'''

# 遞歸函數(shù)

def fact(n):

    if n==1: #2.遞歸函數(shù)中一定要有邊界條件

        return 1

    return fact(n-1)*n # 1.遞歸函數(shù)中一定要有對函數(shù)自己的調(diào)用

print(fact(5))

'''切片'''

'''

names = ['趙夢冰','張榮亮','侯富君','王顏麗','焦新瑞','張國榮','呂煜海

names[a:b:c]表示截取從下標(biāo)a開始到下標(biāo)b結(jié)束的所有的元素，但是包含a不包含b

c 表示步長，默認(rèn)值時1

列表切片后還是列表

元組切片后還是元組

字符串切片還是字符串

print(names[0:3])

print(names[-7:-4]) #切片支持負(fù)數(shù)索引

print(names[2:])

print(names[:3])# 如果第一個0時，可以省略

print(names[:3])# 如果一直截取到末尾，可以省略第二個索引

# 復(fù)制列表

l = names[:]

m = names

print('------------------------------------------')

m.append('白李娜')

print(names)

print(l)

print(m)

# 切片時還可以指定步長，步長值默認(rèn)是1

print(names[::2])

'''

元組也可以切片，結(jié)果還是字符串

names = ('趙夢冰','張榮亮','侯富君','王顏麗','焦新瑞','張國榮','呂煜海')

print(names[0:3])

字符串也可以切片，結(jié)果還是字符串

s = 'abcdef'

print(s[1:3])

'''迭代'''

names = ['趙夢冰','張榮亮','侯富君','王顏麗','焦新瑞','張國榮','呂煜海']

循環(huán)，遍歷，迭代Iteration

names:可迭代對象

可迭代對象:列表，元組，字典，字符串

for name in names:

    print(name)

print('---------------------')

# 遍歷key

name_scores = {'趙夢冰':88,'張榮亮':99,'侯富君':77,'王顏麗':89,'焦新瑞':93,'張國榮':98,'呂煜海':85}

for key in name_scores:

     print(key)

# name_scores = {'趙夢冰':88,'張榮亮':99,'侯富君':77,'王顏麗':89,'焦新瑞':93,'張國榮':98,'呂煜海':85}

for key in name_scores:

     print(key,name_scores[key])

print('---------------------')

# 遍歷value

for value in name_scores.values():

     print(value)

# 同時遍歷key和value

for key,value in name_scores.items():

    print(key,value)

# 遍歷字符串

for char in 'abcdef':

     print(char)

'''如何判斷一個對象是可迭代對象'''

from collections.abc import Iterable

isinstance(obj,type)判斷對象obj是否是type類型，是則true，否則false

print(isinstance(1,int))

print(isinstance('1',int))

print(isinstance('1',str))

print(isinstance(names,Iterable))

i = 0  #循環(huán)控制變量

for char in 'abcdef':

   print(i,char)

     i = i + 1

# # 簡化方式提供循環(huán)遍歷

# for i,char in enumerate('abcdef'):

#     print(i,char)

'''列表生成式'''

nums = [0,1,2,3,4,5,6,7,8,9]

nums = list(range(6,10))

nums = list(range(10))

print(nums)

# 方法一

# [1*1,2*2,3*3,....,9*9]

nums = [1*1,2*2,3*3,9*9]

# 方法二

nums = []

for x in range(1,10):

     nums.append(x*x)

print(nums)

# 方法三 -列表生成式

# m = [x*x for x in range(1,10)]

# print(m)

m = [1/n for n in range(1,10)]

print(m)

# 列表生成式中添加條件判斷

o = [x*x for x in range(1,10) if x%2==0]

print(o)

# 列表生成式中使用多重循環(huán)

p = [x+y for x in 'ABC' for y in 'xyz']

print(p)

q = list([x*x for x in range(1,10)])

print(q)

q = tuple([x*x for x in range(1,10)])

print(q)

q = dict([x*x for x in range(1,10)])

print(q)