python学习---文件修改

1、读一行，写一行，判断字符串，修改之。

 f=open("yesterday2","r",encoding="utf-8")
 f_new=open("yesterday3","w",encoding="utf-8")

 for line in f:
     if "爱情触手可及" in line:
         line=line.replace("爱情触手可及","爱情触手不可极")
     f_new.write(line)
 f.close
 f_new.close

 import sys
 f=open("yesterday2","r",encoding="utf-8")
 f_new=open("yesterday3","w",encoding="utf-8") 

 find_str=sys.argv[1]
 replace_str=sys.argv[2]

 for line in f:
      if find_str in line:
          line=line.replace(find_str,replace_str)
      f_new.write(line)
 f.close
 f_new.close

2、with语句打开文件的文法

 #f=open("yesterday2","r",encoding="utf-8")
 with open("yesterday2","r",encoding="utf-8") as f:
     for line in f:
         print (line)