[ 文件操作]
1 对文件操作流程
- 打开文件，得到文件句柄并赋值给一个变量
- 通过句柄对文件进行操作
- 关闭文件
现有文件如下：
昨夜寒蛩不住鸣。 惊回千里梦，已三更。 起来独自绕阶行。 人悄悄，帘外月胧明。 白首为功名，旧山松竹老，阻归程。 欲将心事付瑶琴。 知音少，弦断有谁听。
f = open('小重山') #打开文件 data=f.read()#获取文件内容 f.close() #关闭文件
2 文件打开模式
========= =============================================================== 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) ========= ===============================================================
先介绍三种最基本的模式：
# f = open('小重山2','w') #打开文件 # f = open('小重山2','a') #打开文件 # f.write('莫等闲1\n') # f.write('白了少年头2\n') # f.write('空悲切!3')
3 文件具体操作
def read(self, size=-1): # known case of _io.FileIO.read """ 注意，不一定能全读回来 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. """ return "" def readline(self, *args, **kwargs): pass def readlines(self, *args, **kwargs): pass def tell(self, *args, **kwargs): # real signature unknown """ Current file position. Can raise OSError for non seekable files. """ pass def seek(self, *args, **kwargs): # real signature unknown """ 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. """ pass def write(self, *args, **kwargs): # real signature unknown """ Write bytes b to file, return number 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. """ pass def flush(self, *args, **kwargs): pass def truncate(self, *args, **kwargs): # real signature unknown """ 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. """ pass def close(self): # real signature unknown; restored from __doc__ """ Close the file. A closed file cannot be used for further I/O operations. close() may be called more than once without error. """ pass ##############################################################less usefull def fileno(self, *args, **kwargs): # real signature unknown """ Return the underlying file descriptor (an integer). """ pass def isatty(self, *args, **kwargs): # real signature unknown """ True if the file is connected to a TTY device. """ pass def readable(self, *args, **kwargs): # real signature unknown """ True if file was opened in a read mode. """ pass def readall(self, *args, **kwargs): # real signature unknown """ 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. """ pass def seekable(self, *args, **kwargs): # real signature unknown """ True if file supports random-access. """ pass def writable(self, *args, **kwargs): # real signature unknown """ True if file was opened in a write mode. """ pass