文件的读取

help(open)

Help on built-in function open in module io:open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)Open file and return a stream.  Raise OSError upon failure.file is either a text or byte string giving the name (and the pathif the file isn't in the current working directory) of the file tobe opened or an integer file descriptor of the file to bewrapped. (If a file descriptor is given, it is closed when thereturned I/O object is closed, unless closefd is set to False.)mode is an optional string that specifies the mode in which the fileis opened. It defaults to 'r' which means open for reading in textmode.  Other common values are 'w' for writing (truncating the file ifit already exists), 'x' for creating and writing to a new file, and'a' for appending (which on some Unix systems, means that all writesappend to the end of the file regardless of the current seek position).In text mode, if encoding is not specified the encoding used is platformdependent: locale.getpreferredencoding(False) is called to get thecurrent locale encoding. (For reading and writing raw bytes use binarymode and leave encoding unspecified.) The available modes are:========= ===============================================================Character Meaning--------- ---------------------------------------------------------------'r'       open for reading (default)'w'       open for writing, truncating the file first'x'       create a new file and open it for writing'a'       open for writing, appending to the end of the file if it exists'b'       binary mode't'       text mode (default)'+'       open a disk file for updating (reading and writing)'U'       universal newline mode (deprecated)========= ===============================================================The default mode is 'rt' (open for reading text). For binary randomaccess, 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' andraises 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 inbinary mode (appending 'b' to the mode argument) return contents asbytes objects without any decoding. In text mode (the default, or when't' is appended to the mode argument), the contents of the file arereturned as strings, the bytes having been first decoded using aplatform-dependent encoding or using the specified encoding if given.'U' mode is deprecated and will raise an exception in future versionsof Python.  It has no effect in Python 3.  Use newline to controluniversal 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 selectline buffering (only usable in text mode), and an integer > 1 to indicatethe size of a fixed-size chunk buffer.  When no buffering argument isgiven, the default buffering policy works as follows:* Binary files are buffered in fixed-size chunks; the size of the bufferis 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 abovefor binary files.encoding is the name of the encoding used to decode or encode thefile. This should only be used in text mode. The default encoding isplatform dependent, but any encoding supported by Python can bepassed.  See the codecs module for the list of supported encodings.errors is an optional string that specifies how encoding errors are tobe 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 ignoreerrors. (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 textmode). It can be None, '', '\n', '\r', and '\r\n'.  It works asfollows:* On input, if newline is None, universal newlines mode isenabled. Lines in the input can end in '\n', '\r', or '\r\n', andthese are translated into '\n' before being returned to thecaller. If it is '', universal newline mode is enabled, but lineendings are returned to the caller untranslated. If it has any ofthe other legal values, input lines are only terminated by the givenstring, and the line ending is returned to the caller untranslated.* On output, if newline is None, any '\n' characters written aretranslated to the system default line separator, os.linesep. Ifnewline is '' or '\n', no translation takes place. If newline is anyof the other legal values, any '\n' characters written are translatedto the given string.If closefd is False, the underlying file descriptor will be kept openwhen the file is closed. This does not work when a file name is givenand must be True in that case.A custom opener can be used by passing a callable as *opener*. Theunderlying file descriptor for the file object is then obtained bycalling *opener* with (*file*, *flags*). *opener* must return an openfile descriptor (passing os.open as *opener* results in functionalitysimilar to passing None).open() returns a file object whose type depends on the mode, andthrough which the standard file operations such as reading and writingare 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 opena file in a binary mode, the returned class varies: in read binarymode, it returns a BufferedReader; in write binary and append binarymodes, it returns a BufferedWriter, and in read/write mode, it returnsa BufferedRandom.It is also possible to use a string or bytearray as a file for bothreading and writing. For strings StringIO can be used like a fileopened in a text mode, and for bytes a BytesIO can be used like a fileopened in a binary mode.

f=open('C:\\Users\\samsung\\Desktop\\hh.txt',encoding='utf-8')

f

<_io.TextIOWrapper name='C:\\Users\\samsung\\Desktop\\hh.txt' mode='r' encoding='utf-8'>

f.read(5)

'人面不知何'

f.read()

'处去，桃花依旧笑春风。\n人生自古谁无死，留取丹青照汗青。'

f.tell()

98

seek（）：文件指针

f.seek(15,0)#从0号开始，偏移量是15

15

f.readline()

'处去，桃花依旧笑春风。\n'

list(f)

['人生自古谁无死，留取丹青照汗青。']

f.seek(0,0)

0

for each_line in f:#按行显示print(each_line)

人面不知何处去，桃花依旧笑春风。人生自古谁无死，留取丹青照汗青。

文件的写入

f=open('C:\\Users\\samsung\\Desktop\\mm.txt','w')

f.write('我爱余红霞')

5

f.close()

一个任务

def save_file(boy,girl,count):file_name_boy='boy_'+str(count)+'.txt'file_name_girl='girl'+str(count)+'.txt'boy_file=open(file_name_boy,'w')girl_file=open(file_name_girl,'w')boy_file.writelines(boy)girl_file.writelines(girl)boy_file.close()girl_file.close()

def split_file(file_name):f=open(file_name,encoding='utf-8')boy=[]girl=[]count=1for each_line in f:if each_line[:6]!='======':#我们进行字符串分割(role,line_spoken)=each_line.split(':',1)if role =='小甲鱼':boy.append(line_spoken)if role =='小客服':girl.append(line_spoken)else:#文件分别保存save_file(boy,girl,count)boy=[]girl=[]count+=1save_file(boy,girl,count)boy=[]girl=[]count+=1f.close()

split_file('C:\\Users\\samsung\\Desktop\\record.txt')

小结:

1. 如果文件不能正确读取，是因为编码问题，python不能识别，设置open函数的encoding=‘utf-8’。
2. 切分文件时发生错误：文件不能有空行；：必须为英文字符。