python读写操作文件
with open(xxx,'r,coding='utf-8') as f: #打开文件赋值给F ，并且执行完了之后不需要 f.close().
在Python 2.7 及以后，with又支持同时对多个文件的上下文进行管理，即：with open('log1') as obj1, open('log2') as obj2:
f.tell #获取指针位置
f.seek(1) #调整指针位置
f.write() #往文件里面些东西 并切指针到最后
r.read() #读文件
f.open('file.name','r+',encoding='utf-8') #以r+模式打开文件 # r+先读完文件再写(往头部写文件)， w+ #清空文件再写 ，x+ #如果文件存在会报错 ，a+ #打开的同时指针已经到最后了（往尾部写文件)。
f.close() #关闭文件
open函数，该函数用于文件处理
操作文件时，一般需要经历如下步骤：
- 打开文件
- 操作文件
一、打开文件
文件句柄 = open('文件路径', '模式')
打开文件时，需要指定文件路径和以何等方式打开文件，打开后，即可获取该文件句柄，日后通过此文件句柄对该文件操作。
打开文件的模式有：
- r ，只读模式【默认】
- w，只写模式【不可读；不存在则创建；存在则清空内容；】
- x， 只写模式【不可读；不存在则创建，存在则报错】
- a， 追加模式【可读； 不存在则创建；存在则只追加内容；】
"+" 表示可以同时读写某个文件
- r+， 读写【可读，可写】
- w+，写读【可读，可写】
- x+ ，写读【可读，可写】
- a+， 写读【可读，可写】
"b"表示以字节的方式操作
- rb 或 r+b
- wb 或 w+b
- xb 或 w+b
- ab 或 a+b
注：以b方式打开时，读取到的内容是字节类型，写入时也需要提供字节类型
python3操作
1 class TextIOWrapper(_TextIOBase): 2 """ 3 Character and line based layer over a BufferedIOBase object, buffer. 4 5 encoding gives the name of the encoding that the stream will be 6 decoded or encoded with. It defaults to locale.getpreferredencoding(False). 7 8 errors determines the strictness of encoding and decoding (see 9 help(codecs.Codec) or the documentation for codecs.register) and 10 defaults to "strict". 11 12 newline controls how line endings are handled. It can be None, '', 13 '\n', '\r', and '\r\n'. It works as follows: 14 15 * On input, if newline is None, universal newlines mode is 16 enabled. Lines in the input can end in '\n', '\r', or '\r\n', and 17 these are translated into '\n' before being returned to the 18 caller. If it is '', universal newline mode is enabled, but line 19 endings are returned to the caller untranslated. If it has any of 20 the other legal values, input lines are only terminated by the given 21 string, and the line ending is returned to the caller untranslated. 22 23 * On output, if newline is None, any '\n' characters written are 24 translated to the system default line separator, os.linesep. If 25 newline is '' or '\n', no translation takes place. If newline is any 26 of the other legal values, any '\n' characters written are translated 27 to the given string. 28 29 If line_buffering is True, a call to flush is implied when a call to 30 write contains a newline character. 31 """ 32 def close(self, *args, **kwargs): # real signature unknown 33 关闭文件 34 pass 35 36 def fileno(self, *args, **kwargs): # real signature unknown 37 文件描述符 38 pass 39 40 def flush(self, *args, **kwargs): # real signature unknown 41 刷新文件内部缓冲区 42 pass 43 44 def isatty(self, *args, **kwargs): # real signature unknown 45 判断文件是否是同意tty设备 46 pass 47 48 def read(self, *args, **kwargs): # real signature unknown 49 读取指定字节数据 50 pass 51 52 def readable(self, *args, **kwargs): # real signature unknown 53 是否可读 54 pass 55 56 def readline(self, *args, **kwargs): # real signature unknown 57 仅读取一行数据 58 pass 59 60 def seek(self, *args, **kwargs): # real signature unknown 61 指定文件中指针位置 62 pass 63 64 def seekable(self, *args, **kwargs): # real signature unknown 65 指针是否可操作 66 pass 67 68 def tell(self, *args, **kwargs): # real signature unknown 69 获取指针位置 70 pass 71 72 def truncate(self, *args, **kwargs): # real signature unknown 73 截断数据，仅保留指定之前数据 74 pass 75 76 def writable(self, *args, **kwargs): # real signature unknown 77 是否可写 78 pass 79 80 def write(self, *args, **kwargs): # real signature unknown 81 写内容 82 pass 83 84 def __getstate__(self, *args, **kwargs): # real signature unknown 85 pass 86 87 def __init__(self, *args, **kwargs): # real signature unknown 88 pass 89 90 @staticmethod # known case of __new__ 91 def __new__(*args, **kwargs): # real signature unknown 92 """ Create and return a new object. See help(type) for accurate signature. """ 93 pass 94 95 def __next__(self, *args, **kwargs): # real signature unknown 96 """ Implement next(self). """ 97 pass 98 99 def __repr__(self, *args, **kwargs): # real signature unknown 100 """ Return repr(self). """ 101 pass 102 103 buffer = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 104 105 closed = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 106 107 encoding = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 108 109 errors = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 110 111 line_buffering = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 112 113 name = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 114 115 newlines = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 116 117 _CHUNK_SIZE = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 118 119 _finalizing = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 120 121 3.x
python2.x
1 class file(object) 2 def close(self): # real signature unknown; restored from __doc__ 3 关闭文件 4 """ 5 close() -> None or (perhaps) an integer. Close the file. 6 7 Sets data attribute .closed to True. A closed file cannot be used for 8 further I/O operations. close() may be called more than once without 9 error. Some kinds of file objects (for example, opened by popen()) 10 may return an exit status upon closing. 11 """ 12 13 def fileno(self): # real signature unknown; restored from __doc__ 14 文件描述符 15 """ 16 fileno() -> integer "file descriptor". 17 18 This is needed for lower-level file interfaces, such os.read(). 19 """ 20 return 0 21 22 def flush(self): # real signature unknown; restored from __doc__ 23 刷新文件内部缓冲区 24 """ flush() -> None. Flush the internal I/O buffer. """ 25 pass 26 27 28 def isatty(self): # real signature unknown; restored from __doc__ 29 判断文件是否是同意tty设备 30 """ isatty() -> true or false. True if the file is connected to a tty device. """ 31 return False 32 33 34 def next(self): # real signature unknown; restored from __doc__ 35 获取下一行数据，不存在，则报错 36 """ x.next() -> the next value, or raise StopIteration """ 37 pass 38 39 def read(self, size=None): # real signature unknown; restored from __doc__ 40 读取指定字节数据 41 """ 42 read([size]) -> read at most size bytes, returned as a string. 43 44 If the size argument is negative or omitted, read until EOF is reached. 45 Notice that when in non-blocking mode, less data than what was requested 46 may be returned, even if no size parameter was given. 47 """ 48 pass 49 50 def readinto(self): # real signature unknown; restored from __doc__ 51 读取到缓冲区，不要用，将被遗弃 52 """ readinto() -> Undocumented. Don't use this; it may go away. """ 53 pass 54 55 def readline(self, size=None): # real signature unknown; restored from __doc__ 56 仅读取一行数据 57 """ 58 readline([size]) -> next line from the file, as a string. 59 60 Retain newline. A non-negative size argument limits the maximum 61 number of bytes to return (an incomplete line may be returned then). 62 Return an empty string at EOF. 63 """ 64 pass 65 66 def readlines(self, size=None): # real signature unknown; restored from __doc__ 67 读取所有数据，并根据换行保存值列表 68 """ 69 readlines([size]) -> list of strings, each a line from the file. 70 71 Call readline() repeatedly and return a list of the lines so read. 72 The optional size argument, if given, is an approximate bound on the 73 total number of bytes in the lines returned. 74 """ 75 return [] 76 77 def seek(self, offset, whence=None): # real signature unknown; restored from __doc__ 78 指定文件中指针位置 79 """ 80 seek(offset[, whence]) -> None. Move to new file position. 81 82 Argument offset is a byte count. Optional argument whence defaults to 83 (offset from start of file, offset should be >= 0); other values are 1 84 (move relative to current position, positive or negative), and 2 (move 85 relative to end of file, usually negative, although many platforms allow 86 seeking beyond the end of a file). If the file is opened in text mode, 87 only offsets returned by tell() are legal. Use of other offsets causes 88 undefined behavior. 89 Note that not all file objects are seekable. 90 """ 91 pass 92 93 def tell(self): # real signature unknown; restored from __doc__ 94 获取当前指针位置 95 """ tell() -> current file position, an integer (may be a long integer). """ 96 pass 97 98 def truncate(self, size=None): # real signature unknown; restored from __doc__ 99 截断数据，仅保留指定之前数据 100 """ 101 truncate([size]) -> None. Truncate the file to at most size bytes. 102 103 Size defaults to the current file position, as returned by tell(). 104 """ 105 pass 106 107 def write(self, p_str): # real signature unknown; restored from __doc__ 108 写内容 109 """ 110 write(str) -> None. Write string str to file. 111 112 Note that due to buffering, flush() or close() may be needed before 113 the file on disk reflects the data written. 114 """ 115 pass 116 117 def writelines(self, sequence_of_strings): # real signature unknown; restored from __doc__ 118 将一个字符串列表写入文件 119 """ 120 writelines(sequence_of_strings) -> None. Write the strings to the file. 121 122 Note that newlines are not added. The sequence can be any iterable object 123 producing strings. This is equivalent to calling write() for each string. 124 """ 125 pass 126 127 def xreadlines(self): # real signature unknown; restored from __doc__ 128 可用于逐行读取文件，非全部 129 """ 130 xreadlines() -> returns self. 131 132 For backward compatibility. File objects now include the performance 133 optimizations previously implemented in the xreadlines module. 134 """ 135 pass 136 137 2.x
