Usage of file and open in Python

What's the difference between file and open?

File is a class, and when opened with the Open function, returns a file object.
file1 = File ("Aa.txt")

File2 = open ("Aa.txt") #这个时候返回的是跟file1一样的对象, can be read to Aa.txt, modify.

Temporarily found that seemingly not much difference, the habit of like to use open.

Python 2 is basically no different. There's no file in Python 3.

In Python 2, file is a document object. Open is the built-in function that returns the newly created file object, which is equivalent to:

def open (*args, **kwargs):
Return file (*args, **kwargs)
Its true definition is:

Static Pyobject *
Builtin_open (Pyobject *self, Pyobject *args, Pyobject *kwds)
{
Return Pyobject_call ((pyobject*) &pyfile_type, args, Kwds);
}

So file is also able to create files.

File and open usages

Help (file) help (Open)

The old rules first look at the built-in help document how to describe file and open, after all, the official document is the most direct and accurate description.

Help on class file in module __builtin__:

class file (object)
| File (name[, mode[, Buffering]])-> file object
|
|  Open a file. The mode can be is ' r ', ' W ' or ' A ' for reading (default),
|  Writing or appending. The file would be created if it doesn ' t exist
| When opened for writing or appending; It'll be truncated when
|  Opened for writing. Add a ' B ' to the "mode for binary files."
| Add a ' + ' to "mode to allow simultaneous reading and writing.
| If The buffering argument is given, 0 means unbuffered, 1 means line
|  Buffered, and larger numbers specify the buffer size. The preferred way
| To open a file are with the Builtin open () function.
| Add a ' U ' to "mode to open" file for input with universal newline
|  Support. Any line ending in the input file would be seen as a ' \ n '
|  In Python. Also, a file so opened gains the attribute ' newlines ';
| The value is one of None (no newline read yet),
| ' \ r ', ' \ n ', ' \ r \ n ' or a tuple containing all the newline types seen.
Simply put, file is a class that uses file (' file_name ', ' r+ ') to open files, return a filename object, open the file in write mode, and it will be created. But it is more recommended to use the built-in function open () to open a file, so let's take a look at the introduction to open ():

Help on built-in function open in module __builtin__:

Open (...)
Open (name[, mode[, buffering])-> file object

The Open a file using the file () type, returns a file object. This is the
Preferred way to open a file. File.__doc__ for further information.
(end)
First Open is a built-in function, which is open (' file_name ', mode, buffering), and the return value is also a file object, and similarly, opening a file in write mode will create a new one if it does not exist.

Working with instances

In [8]: f1 = open (' test.py ')                                                                                                                                                                               

In [9]: F1.
f1.close       f1.fileno      f1.name         f1.readinto    f1.softspace   f1.writelines
f1.closed       f1.flush       f1.newlines    f1.readline    f1.tell        f1.xreadlines
f1.encoding     f1.isatty      f1.next        f1.readlines   f1.truncate   
f1.errors      f1.mode         f1.read        f1.seek         f1.write      

In [9]: F1.rea
F1.read F1.readinto F1.readline F1.readlines

In [9]: F1.readli
F1.readline F1.readlines

In [9]: F1.readlines ()
OUT[9]:
[' Import logging\n ',
' \ n ',
"Logging.basicconfig (filename= ' Test.log ', level=logging.info) \ n",
"Logging.info (' started ') \ n",
"Print ' x ' + 1\n",
"Logging.info (' finished ') \ n"]

In [ten]: f1.cl
F1.close f1.closed

In [ten]: F1.close ()

In [one]: F2 = file (' test.py ')                                                                                                                                                                              

in [[]: F2.
f2.close       f2.fileno      f2.name         f2.readinto    f2.softspace   f2.writelines
f2.closed       f2.flush       f2.newlines    f2.readline    f2.tell        f2.xreadlines
f2.encoding     f2.isatty      f2.next        f2.readlines   f2.truncate   
f2.errors      f2.mode         f2.read        f2.seek         f2.write      

in [[]: F2.read
F2.read F2.readinto F2.readline F2.readlines

in [[]: F2.readli
F2.readline F2.readlines

in [[]: F2.readlines ()
OUT[12]:
[' Import logging\n ',
' \ n ',
"Logging.basicconfig (filename= ' Test.log ', level=logging.info) \ n",
"Logging.info (' started ') \ n",
"Print ' x ' + 1\n",
"Logging.info (' finished ') \ n"]

in [+]: f2.cl
F2.close f2.closed

in [[]: F2.closed ()
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-13-24c97e0e079e> in <module> ()
----> 1 f2.closed ()

TypeError: ' bool ' object is not callable

in [/]: f2.closed
OUT[14]: False

in [[]: F2.close ()

# Open files that don't exist

in [[]: F3 = File (' txt.txt ', ' r+ ')
---------------------------------------------------------------------------
IOError Traceback (most recent call last)
<ipython-input-18-3e9262877eea> in <module> ()
----> 1 f3 = File (' txt.txt ', ' r+ ')

IOError: [Errno 2] No such file or directory: ' Txt.txt '

in [[]: F3 = File (' txt.txt ', ' w+ ')
Can be seen to use when the difference is not very small, but note that Py3 has no file~ this may also be the recommended use of open a very important reason for it