PYTHON：关闭文件的 I/O 操作

Question

我相信这一切都与缩进有关，但我不确定如何准确缩进，请帮助我。import csvwith open('abbreviations.csv', mode='r') as infile:   reader = csv.reader(infile)with open('abbreviations_new.csv', mode='w') as outfile:   writer = csv.writer(outfile)   mydict = {rows[0]:rows[1] for rows in reader}   print(len(mydict))   print(mydict['v'])   mydict['MIS'] = 'Management Information System'   print(mydict['TA'])   mydict['TA'] = 'teaching assistant'   print(mydict['TA'])   print(mydict['flower'])   del mydict['flower']

Answer 1

试试这个方法

import csv

with open('abbreviations.csv', mode='r') as infile:

   reader = csv.reader(infile)

   with open('abbreviations_new.csv', mode='w') as outfile:

       writer = csv.writer(outfile)

       mydict = {rows[0]:rows[1] for rows in reader}

       print(len(mydict))

       print(mydict['v'])

       mydict['MIS'] = 'Management Information System'

       print(mydict['TA'])

       mydict['TA'] = 'teaching assistant'

       print(mydict['TA'])

       print(mydict['flower'])

       del mydict['flower']

当您使用 with open 时，循环结束时文件会自动关闭。

Answer 2

您可以使用

with open('abbreviations.csv', mode='r') as infile, open(  # you can put two opens after 

          'abbreviations_new.csv', mode='w') as outfile:   # one with statement

    reader = csv.reader(infile)

    writer = csv.writer(outfile)

    mydict = {rows[0]:rows[1] for rows in reader}

    print(len(mydict))

    print(mydict['v'])

    mydict['MIS'] = 'Management Information System'

    print(mydict['TA'])

    mydict['TA'] = 'teaching assistant'

    print(mydict['TA'])

    print(mydict['flower'])

    del mydict['flower']

# on this indentation level the files are closed

一旦您离开with open(...) as f:文件的缩进，文件就会自动关闭。