#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:ZhengzhengLiu
f = open("song",'r',encoding="utf-8")
f_new = open("song2.txt",'w',encoding="utf-8")  #打开一个新文件(往里面写内容)
for line in f:
  if "其实爱我真的很简单" in line:
    line = line.replace("其实爱我真的很简单","其实爱你真的很简单")
  f_new.write(line)
f.close()
f_new.close()

#为了避免打开文件后忘记关闭，可以通过with语句管理上下文
with open("song",'r',encoding="utf-8") as f:
  for line in f:
    print(line)

#打开多个文件
with open("song",'r',encoding="utf-8") as f,    open("song2",'r',encoding="utf-8") as f2:
  for line in f:
    print(line)