day10上节内容补充和初始函数

1.上节内容补充

　　 文件的删除和修改：

#文件的删除和修改
#文件中全部都要修改
# with open('歌词',encoding='utf-8') as f1,open('歌词.bak','w',encoding='utf-8') as f2:
#     for line in f1:
#         new_line = line.replace('呢','呀')
#         f2.write(new_line)
# import os
# os.remove('歌词')
# os.rename('歌词.bak','歌词')
#第二种  某一行要修改  比如第一个出现呢的行
with open('歌词',encoding='utf-8') as f1,open('歌词.bak','w',encoding='utf-8') as f2:
    flag = True # count = 0
    for line in f1:
        if '呀' in line and flag: # if '呀' in line and coun==0
            new_line = line.replace('呀','呢')
            f2.write(new_line)
            flag = False                   # count+=1
        else:
            f2.write(line)
import os                             # 文件的删除接触windows系统的删除 用到了模块
os.remove('歌词')
os.rename('歌词.bak','歌词')

      文件操作with 体的使用