1、输出当前目录下的所有文件和文件名

import os
filename = os.listdir()
print(filename)

2、判断奇偶数

numbers = [34,57,12,43,3,5,8,193,22]
for number in numbers:
    if number%2 == 0:
        print(f'{number}是偶数')
    else:
        print(f'{number}是奇数')

3、判断字符串是否只由数字组成

s = 'hello123'     # 字符串不只是由数字组成的情况，返回False
print(s.isdigit())

s1 = '123'
print(s1.isdigit())    # 字符串只由数字组成的情况，返回True

4、合并去重

lst1 = [1,2,3,4,5,6]
lst2 = [3,4,5,6,7,8,9]
lst3 = lst1 + lst2
print(list(set(lst3)))

5、打印九九乘法表

for i in range(1,10):
    for j in range(1,i+1):
        print(f'{i}*{j}={i*j}',end=' ')
    print()

6、把一个list中所有的字符串变成小写

# 第一种方法
print('{:-^50}'.format('first method'))
lst = ['PYTHON','Spider','pandas','Urllib','REQUESTS']
li = []
for i in range(len(lst)):
    li.append(lst[i].lower())
print(li)

# 第二种方法（推荐）
print('{:-^50}'.format('second method'))
lst = ['PYTHON','Spider','pandas','Urllib','REQUESTS']
lst = ','.join(lst).lower().split(',')
print(lst)

7、把原字典的键值对颠倒并产生新的字典

d1 = {1:'a',2:'b',3:'c'}
d2 = {}
for i in d1.items():
    d2[i[1]] = i[0]
print(d2)

8、替换列表中所有的3为3a

lst = [1,'python','b',3,'hello',3,12,'world',3]
for i in range(len(lst)):
    if lst[i] == 3:
        lst[i] = '3a'
print(lst)

9、计算x的n次方的方法

def method(x,n):
    print(x**n)
method(9,3)

10、输出某个路径下的所有文件和文件夹的路径

import os
filepath = r'C:\Users\A\Desktop\pythonone'
paths = os.listdir(filepath)
for path in paths:
    print(filepath+path)