Python 初始—(文件操作)

文件修改，我们可以不用讲一个文件全部都进行读取，然后放入内存，如果文件过大，容易造成内存的

内存溢出问题

 

因此我们可以便读取边进行修改操作

f=open("old.txt","r",encoding="utf-8")
f_new=open("new.txt","w",encoding="utf-8")
for line in f:
    if "微笑在天上" in line:
        line=line.replace("微笑在天上","开心在心中");
    f_new.write(line)
f.close()
f_new.close()

同时我们也可以将关闭文件的动作交给With来实现:
  with open("new.txt","w",encoding="utf-8") as f:
       for line in f:
           print(line)