凯撒加密解密
凯撒加密解密,偏移量为13
mode = input("输入 encode(解密) 或 decode(加密) :") if ('decode' or 'encode') in mode: tran = '' key = 13 #偏移量 13 LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' mess = input('输入编码:') mess = mess.upper() print("开始"+mode+':') for symbol in mess: if symbol in LETTERS: num = LETTERS.find(symbol) if mode == 'encode': num = num + key elif mode == 'decode': num = num - key if num >= len(LETTERS): num = num -len(LETTERS) elif num < 0: num = num + len(LETTERS) tran = tran + LETTERS[num] else: tran = tran + symbol print(tran.lower()) else: print('输入错误......')