可以使用同一个文件对象多次读取文件吗？

Question

在Python中，当您使用open方法打开文件时，它会返回文件对象。我们可以使用这个对象来多次读取吗？

如果是，那么为什么它对我不起作用。我使用的是pyhon2.7.2版本

 from sys import argv

 script, filename = argv

 txt = open(filename)

 print "Here is your file %r" % filename
 # Reads the complete file into the txt variable
 print txt.read()
 # Here i am using txt file object again to read byte by byte of the file
 # which doesn't seem to be working.
 print txt.read(1)

它不工作的任何原因？

Answer 1

当然。要将“光标”移回到开头，请执行以下操作：

txt.seek(0)

文件：

seek(offset[, whence]) -> None.  Move to new file position.

Argument offset is a byte count.  Optional argument whence defaults to
0 (offset from start of file, offset should be >= 0); other values are 1
(move relative to current position, positive or negative), and 2 (move
relative to end of file, usually negative, although many platforms allow
seeking beyond the end of a file).  If the file is opened in text mode,
only offsets returned by tell() are legal.  Use of other offsets causes
undefined behavior.
Note that not all file objects are seekable.