文件操作

fr = open('Alice.txt', mode='r', encoding='utf-8')
plaincode=fr.read()
print('明文:'+plaincode)

print('密文：',end='')
for c in plaincode:
    print(chr(ord(c)+3),end='')

fr = open('Alice.txt', mode='r', encoding='utf-8')
plaincode=fr.read()
fr.close()

fw = open('c_Alice.txt',mode='a', encoding='utf-8')
for c in plaincode:
    fw.write(chr(ord(c)+3))
fw.close()

fr = open('c_Alice.txt', mode='r', encoding='utf-8')
plaincode=fr.read()
fr.close()

fw = open('Alice.txt',mode='a', encoding='utf-8')
for c in plaincode:
    fw.write(chr(ord(c)-3))
fw.close()

classmates = ['Michael','Bob','Tracy']
#print(len(classmates))
#print(classmates[-1])

classmates.append('Rose')
print(classmates)

classmates = ['Michael','Bob','Tracy']
#print(len(classmates))
#print(classmates[-1])

classmates.append('Rose')
classmates.insert(1,'Jack')

classmates.pop()
print(classmates)

classmates = ['Michael','Bob','Tracy']
#print(len(classmates))
#print(classmates[-1])

classmates.append('Rose')
classmates.insert(1,'Jack')

classmates.pop()
classmates.pop(0)
print(classmates)

classmates = ['Michael','Bob','Tracy']
#print(len(classmates))
#print(classmates[-1])

classmates.append('Rose')
classmates.insert(1,'Jack')

classmates.pop()
classmates.pop(0)
classmates[0] ='Tom'
print(classmates)

import turtle
turtle.speed(10)
colors = ['red', 'purple', 'blue', 'green', 'yellow', 'orange']

for i in range(100):
    turtle.pencolor(colors[i% 6])
    turtle.forward(i)
    turtle.left(59)
turtle.done()