try-except 与文件句柄（在哪里关闭）

Question

Suppose I want to introduce a try-except block while handling a txt file. Which of the two following way of capturing the possible exception is correct?

try:
    h = open(filename)
except:
    h.close()
    print('Could not read file')



try:
    h = open(filename)
except:
  
    print('Could not read file')

In other words, should the h.close() be called even if the exception occurs or not?

Secondly, suppose that you have the following code

try:
    h = open(filename)
    "code line here1"
    "code line here2"
except:
    h.close()
    print('Could not read file')

If an error occurs in "code line here1", should I use h.close() in the except block?

Is there a difference with the previous coding lines?

Answer 1

You should use with , it will close the file appropriately:

with open(filename) as h:
   #
   # do whatever you need...
   # 
# when you get here, the file will be closed automatically.

You can enclose that in a try/except block if needed. The file will always be properly closed.