The use of the Seek () method for manipulating files in Python

This article mainly introduces the use of the Seek () method of manipulating files in Python, which is the basic knowledge of Python's introductory study, and needs friends to refer to the

The Seek () method sets the current position of the file at the offset. The parameter is optional, the default is 0, which means absolute file positioning, and its value if 1, which means seeking relative to the current position, and 2 representing the end of the file.

no return value. Note that if the file is opened or is appended with a ' a ' or ' A + ', any seek () action will be undone at the next write.

If the file only opens in Append mode written with "a", this method is essentially an empty operation, but read-enabled (mode ' + ') is still useful for files that are open in Append mode.

If the file uses "T" in text mode, only the deviation from tell () returned is legal. Using other offsets can result in an indeterminate behavior.

Note that not all file objects are searchable.

Grammar

The following is the syntax for the Seek () method:

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1	Fileobject.seek (offset[, whence])

Parameters

Offset-This is the position of the read/write pointer in the file.

Whence--This is optional, the default is 0, which means absolute file positioning, and the other value is 1, which means seeking relative to the current position, and 2 representing the end of the file.

return value

This method does not return any values.

Example

The following example shows the use of the Seek () method.

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#!/usr/bin/python # Open a file fo = open ("Foo.txt", "rw+") print "Name of the file:", Fo.name # assuming file has fo Llowing 5 Lines # this are 1st line # this is 2nd line # this is 3rd line # the IS 4th . ReadLine () print "Read line:%s"% [line] # Again Set the pointer to the beginning Fo.seek (0, 0) line = fo.readline () p Rint ' Read line:%s '% (line) # Close Opend file Fo.close ()

When we run the above program, it produces the following results:

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Name of the File:foo.txt read Line:this is 1st line Read Line:this