파이썬 파일 입출력 help, dir
파이썬 파일 입출력에 대해서 help 함수를 이용하고 싶은데 나오지 않죠?
아마 이런 에러코드를 뿜을 겁니다.
>>> help(read())
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'read' is not defined
#===================================#
>>> help(write())
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'write' is not defined분명히 import 없이 사용가능한 함수인데 왜 그럴까 찾아보니, file타입이 파이썬 3에 오면서 삭제되었다는군요.
그대신 import sys를 할 경우 볼 수 있는 io모듈을 이용하여 파일 입출력 함수의 도움말을 찾을 수 있습니다.
import io
print(dir(io))
print(help(io.FileIO))저는 이렇게 찾았습니다.
io는
import sys
print(dir(sys))를 통해 찾았습니다.
dir로 어떤 메서드가 있는 지 보고, FileIO 가 적합해 보여서 이걸 help함수의 인수로 넣었습니다.
글 맨 끝에 FileIO에 대한 help 결과를 적어서 둘테니 열어보시면 됩니다.
read, write함수 말고 readline, seek 등의 여러 함수들에 대한 설명도 있으니 읽어보시면 좋습니다.
궁금했던 write, read에 대한 help입니다.
write(self, b, /)
| Write buffer b to file, return number of bytes written.
|
| Only makes one system call, so not all of the data may be written.
| The number of bytes actually written is returned. In non-blocking mode,
| returns None if the write would block.read(self, size=-1, /)
| Read at most size bytes, returned as bytes.
|
| Only makes one system call, so less data may be returned than requested.
| In non-blocking mode, returns None if no data is available.
| Return an empty bytes object at EOF.read의 경우 아시다시피 EOF 반환이라고 적혀있네요. only makes one system call 이라는 부분도 눈에 들어옵니다.
class FileIO(_RawIOBase)
| FileIO(file, mode='r', closefd=True, opener=None)
|
| Open a file.
|
| The mode can be 'r' (default), 'w', 'x' or 'a' for reading,
| writing, exclusive creation or appending. The file will be created if it
| doesn't exist when opened for writing or appending; it will be truncated
| when opened for writing. A FileExistsError will be raised if it already
| exists when opened for creating. Opening a file for creating implies
| writing so this mode behaves in a similar way to 'w'.Add a '+' to the mode
| to allow simultaneous reading and writing. A custom opener can be used by
| passing a callable as *opener*. The underlying file descriptor for the file
| object is then obtained by calling opener with (*name*, *flags*).
| *opener* must return an open file descriptor (passing os.open as *opener*
| results in functionality similar to passing None).
|
| Method resolution order:
| FileIO
| _RawIOBase
| _IOBase
| builtins.object
|
| Methods defined here:
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __getstate__(...)
|
| __init__(self, /, *args, **kwargs)
| Initialize self. See help(type(self)) for accurate signature.
|
| __repr__(self, /)
| Return repr(self).
|
| close(self, /)
| Close the file.
|
| A closed file cannot be used for further I/O operations. close() may be
| called more than once without error.
|
| fileno(self, /)
| Return the underlying file descriptor (an integer).
|
| isatty(self, /)
| True if the file is connected to a TTY device.
|
| read(self, size=-1, /)
| Read at most size bytes, returned as bytes.
|
| Only makes one system call, so less data may be returned than requested.
| In non-blocking mode, returns None if no data is available.
| Return an empty bytes object at EOF.
|
| readable(self, /)
| True if file was opened in a read mode.
|
| readall(self, /)
| Read all data from the file, returned as bytes.
|
| In non-blocking mode, returns as much as is immediately available,
| or None if no data is available. Return an empty bytes object at EOF.
|
| readinto(self, buffer, /)
| Same as RawIOBase.readinto().
|
| seek(self, pos, whence=0, /)
| Move to new file position and return the file position.
|
| Argument offset is a byte count. Optional argument whence defaults to
| SEEK_SET or 0 (offset from start of file, offset should be >= 0); other values
| are SEEK_CUR or 1 (move relative to current position, positive or negative),
| and SEEK_END or 2 (move relative to end of file, usually negative, although
| many platforms allow seeking beyond the end of a file).
|
| Note that not all file objects are seekable.
|
| seekable(self, /)
| True if file supports random-access.
|
| tell(self, /)
| Current file position.
|
| Can raise OSError for non seekable files.
|
| truncate(self, size=None, /)
| Truncate the file to at most size bytes and return the truncated size.
|
| Size defaults to the current file position, as returned by tell().
| The current file position is changed to the value of size.
|
| writable(self, /)
| True if file was opened in a write mode.
|
| write(self, b, /)
| Write buffer b to file, return number of bytes written.
|
| Only makes one system call, so not all of the data may be written.
| The number of bytes actually written is returned. In non-blocking mode,
| returns None if the write would block.
|
| ----------------------------------------------------------------------
| Static methods defined here:
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| closed
| True if the file is closed
|
| closefd
| True if the file descriptor will be closed by close().
|
| mode
| String giving the file mode
|
| ----------------------------------------------------------------------
| Methods inherited from _IOBase:
|
| __del__(...)
|
| __enter__(...)
|
| __exit__(...)
|
| __iter__(self, /)
| Implement iter(self).
|
| __next__(self, /)
| Implement next(self).
|
| flush(self, /)
| Flush write buffers, if applicable.
|
| This is not implemented for read-only and non-blocking streams.
|
| readline(self, size=-1, /)
| Read and return a line from the stream.
|
| If size is specified, at most size bytes will be read.
|
| The line terminator is always b'\n' for binary files; for text
| files, the newlines argument to open can be used to select the line
| terminator(s) recognized.
|
| readlines(self, hint=-1, /)
| Return a list of lines from the stream.
|
| hint can be specified to control the number of lines read: no more
| lines will be read if the total size (in bytes/characters) of all
| lines so far exceeds hint.
|
| writelines(self, lines, /)
|
| ----------------------------------------------------------------------
| Data descriptors inherited from _IOBase:
|
| __dict__
"댓글, 공감 버튼 한 번씩 누르고 가주시면 큰 힘이 됩니다"
