注：最后有面试挑战，看看自己掌握了吗
文章目录
- 文本文件
- 建立文件
- open函数详解
- 注意：
- 读写文本文件
- 一次写入多行
- 以列表形式读取多行
- 在指定位置读写
- 文件操作异常处理
文本文件
文本文件有初步存放编辑数据的能力，可以保存和共享。
建立文件
open()函数-----考虑文本名称，本身是一个字符串，需要考虑转义符号对路径或名称的影响，比如：t被识别为制表符号
file = open('d:t1.txt','w')
file.write('无敌坤坤爱你')
file.close()
OSError: [Errno 22] Invalid argument: 'd:t1.txt'解决方案：用’d:\t1.txt' 或者 r'd:t1.txt'
用b_new_file.close()把新建的文件关闭------？没找到 不然一直留存在内存中。
open函数详解
rwxa 与 bt U这几个模式混合使用
注意：
open可以打开二进制文件包括--------图片、exe-----这就有了无限的想象空间，修改图片内容，往exe里面加点特殊代码~~但是对exe文件进行操作有时很有风险，需要谨慎。
代码语言：javascript复制def open(file, mode='r', buffering=None, encoding=None, errors=None, newline=None, closefd=True): # known special case of open
"""
Open file and return a stream. Raise OSError upon failure.
打开文件并返回一个流。在失败时引发错误。
file is either a text or byte string giving the name (and the path
if the file isn't in the current working directory) of the file to
be opened or an integer file descriptor of the file to be
wrapped. (If a file descriptor is given, it is closed when the
returned I/O object is closed, unless closefd is set to False.)
File 是一个文本或字节字符串，提供名称(和路径)如果该文件不在当前工作目录中，则返回或文件的整数文件描述符包好了
mode is an optional string that specifies the mode in which the file
is opened. It defaults to 'r' which means open for reading in text
mode. Other common values are 'w' for writing (truncating the file if
it already exists), 'x' for creating and writing to a new file, and
'a' for appending (which on some Unix systems, means that all writes
append to the end of the file regardless of the current seek position).
In text mode, if encoding is not specified the encoding used is platform
dependent: locale.getpreferredencoding(False) is called to get the
current locale encoding. (For reading and writing raw bytes use binary
mode and leave encoding unspecified.) The available modes are:
========= ===============================================================
Character Meaning
--------- ---------------------------------------------------------------
'r' open for reading (default)
'w' open for writing, truncating the file first打开以便写入，首先截断文件
'x' create a new file and open it for writing创建一个新文件并打开它进行写入
'a' open for writing, appending to the end of the file if it exists打开以进行写入，如果文件存在，则追加到文件末尾
'b' binary mode
't' text mode (default)
' ' open a disk file for updating (reading and writing)打开磁盘文件进行更新(读写)
'U' universal newline mode (deprecated)
========= ===============================================================
The default mode is 'rt' (open for reading text). For binary random
access, the mode 'w b' opens and truncates the file to 0 bytes, while
'r b' opens the file without truncation. The 'x' mode implies 'w' and
raises an `FileExistsError` if the file already exists.
Python distinguishes between files opened in binary and text modes,
even when the underlying operating system doesn't. Files opened in
binary mode (appending 'b' to the mode argument) return contents as
bytes objects without any decoding. In text mode (the default, or when
't' is appended to the mode argument), the contents of the file are
returned as strings, the bytes having been first decoded using a
platform-dependent encoding or using the specified encoding if given.
'U' mode is deprecated and will raise an exception in future versions
of Python. It has no effect in Python 3. Use newline to control
universal newlines mode.
buffering is an optional integer used to set the buffering policy.
Pass 0 to switch buffering off (only allowed in binary mode), 1 to select
line buffering (only usable in text mode), and an integer > 1 to indicate
the size of a fixed-size chunk buffer. When no buffering argument is
given, the default buffering policy works as follows:
* Binary files are buffered in fixed-size chunks; the size of the buffer
is chosen using a heuristic trying to determine the underlying device's
"block size" and falling back on `io.DEFAULT_BUFFER_SIZE`.
On many systems, the buffer will typically be 4096 or 8192 bytes long.
* "Interactive" text files (files for which isatty() returns True)
use line buffering. Other text files use the policy described above
for binary files.
encoding is the name of the encoding used to decode or encode the
file. This should only be used in text mode. The default encoding is
platform dependent, but any encoding supported by Python can be
passed. See the codecs module for the list of supported encodings.
errors is an optional string that specifies how encoding errors are to
be handled---this argument should not be used in binary mode. Pass
'strict' to raise a ValueError exception if there is an encoding error
(the default of None has the same effect), or pass 'ignore' to ignore
errors. (Note that ignoring encoding errors can lead to data loss.)
See the documentation for codecs.register or run 'help(codecs.Codec)'
for a list of the permitted encoding error strings.
newline controls how universal newlines works (it only applies to text
mode). It can be None, '', 'n', 'r', and 'rn'. It works as
follows:
* On input, if newline is None, universal newlines mode is
enabled. Lines in the input can end in 'n', 'r', or 'rn', and
these are translated into 'n' before being returned to the
caller. If it is '', universal newline mode is enabled, but line
endings are returned to the caller untranslated. If it has any of
the other legal values, input lines are only terminated by the given
string, and the line ending is returned to the caller untranslated.
* On output, if newline is None, any 'n' characters written are
translated to the system default line separator, os.linesep. If
newline is '' or 'n', no translation takes place. If newline is any
of the other legal values, any 'n' characters written are translated
to the given string.
If closefd is False, the underlying file descriptor will be kept open
when the file is closed. This does not work when a file name is given
and must be True in that case.
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 (*file*, *flags*). *opener* must return an open
file descriptor (passing os.open as *opener* results in functionality
similar to passing None).
open() returns a file object whose type depends on the mode, and
through which the standard file operations such as reading and writing
are performed. When open() is used to open a file in a text mode ('w',
'r', 'wt', 'rt', etc.), it returns a TextIOWrapper. When used to open
a file in a binary mode, the returned class varies: in read binary
mode, it returns a BufferedReader; in write binary and append binary
modes, it returns a BufferedWriter, and in read/write mode, it returns
a BufferedRandom.
Open ()返回一个文件对象，其类型取决于模式，并且
通过它进行读写等标准文件操作
当 open ()用于以文本模式(‘ w’,
‘ r’、‘ wt’、‘ rt’等) ，它返回一个 TextIOWrapper
在二进制模式下，返回的类变化: 在读取二进制模式下
模式下，它返回一个 BufferedReader; 在写入二进制文件和追加二进制文件中
模式下，它返回一个 BufferedWriter，在读/写模式下，它返回
一个 BufferedRandom。
It is also possible to use a string or bytearray as a file for both
reading and writing. For strings StringIO can be used like a file
opened in a text mode, and for bytes a BytesIO can be used like a file
opened in a binary mode.
"""
pass
