文件操作

classmates = ['Michael','Bob','Tracy']

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()

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