fr = open('fjq.txt',mode='r',encoding='utf-8')fjq = fr.read()print('明文：'+ljy)print('密文：',end='')fw = open('cipherText.txt',mode='a',encoding='utf-8')for c in fjq:    print(chr(ord(c)+3),end='')    fw.write(chr(ord(c)+3))fr.close()fw.close()

fjq = open('plainText.txt',mode='r', encoding='utf-8')plainText = fjq.read()print('明文：'+plainText)print('密文：',end='')for c in plainText:    print(chr(ord(c)+3),end='')for c in plainText:    print(chr(ord(c)+3),end='')