用Python逐行编写一个文本文件

Question

我需要逐行写一个文本文件.此代码逐行打印文本,但只有最后一行存储在result.txt文件中.

import re
import fileinput
for line in fileinput.input("test.txt"):
    new_str = re.sub('[^a-zA-Z0-9\n\.]'," ", line)
    print new_str
open('result.txt', 'w').write(new_str)

Answer 1

1. 我不知道为什么你需要fileinput模块,open也可以处理这种情况.

2. 你的for循环遍历所有行并覆盖 new_str新行.最后一行没有下一行,因此不会被覆盖,因此它是唯一可以保存的行.

   import re
   test_f = open('test.txt')
   result_f = open('result.txt', 'a')
   for line in test_f:
       new_str = re.sub('[^a-zA-Z0-9\n\.]'," ", line)
       result_f.write(new_str)
   
   # also, this too, please:
   test_f.close()
   result_f.close()
   

3. with即使代码崩溃,您也应该使用该语句自动关闭文件.

   import re
   with open('test.txt') as test_f, open('result.txt', 'w') as result_f:
       for line in test_f:
           new_str = re.sub('[^a-zA-Z0-9\n\.]'," ", line)
           result_f.write(new_str)