Python：打开并写入.txt文件

Question

I'm new to python and so I'm trying to make an ATM (simulator I guess). One of the functions is to register, and so I'm trying to save the usernames in a .txt file for reference (passwords will come later of course), but for some reason it won't work.

def atm_register():
print "To register, please choose a username."

username = raw_input('> ')

with open("users.txt") as f:
    f.write(username, "a")

It tells me, that the file is not open for writing. Btw, the users.txt file is in the same directory as the program.

Answer 1

我认为应该是：

open("users.txt","w")

Answer 2

You should use

with open("users.txt","a") as f:
      f.write(username)

instead of

with open("users.txt") as f:
     f.write(username, "a")

hope this helps!

Answer 3

You must open the file in write mode. See the documentation for open

open('users.txt', 'w') should work.

Answer 4

Given that you're calling f.write(username, "a") and file write() only takes one parameter - the text to write - I guess you intend the "a" to append to the file?

That goes in the open() call; other answers telling you to use open(name, "w") are bad advice, as they will overwrite the existing file. And you might want to write a newline after the username, too, to keep the file tidy. eg

with open("users.txt", "a") as f:
    f.write(username + "\n")