def encryption():
str_raw = input("请输入明文:")
k = int(input("请输入位移值:"))
str_change = str_raw.lower()
str_list = list(str_change)
str_list_encry = str_list
i = 0
while i < len(str_list):
if ord(str_list[i]) < 123-k:
str_list_encry[i] = chr(ord(str_list[i]) + k)
else:
print ("解密结果为:"+"".join(str_list_decry))
while True:
print (u"1. 加密")
print(u"2. 解密")
choice = input("请选择:")
if choice == "1": encryption()
elif choice == "2": decryption()
else: print (u"您的输入有误!")
