Python3 File seek() Method

Python3 File(文件) 方法Python3 File Methods

Overview

seek()The method is used to move the file read pointer to a specified position.

Syntax

The syntax of the seek() method is as follows:

fileObject.seek(offset[, whence])

Parameters

  • offset-- The starting offset, which represents the number of bytes to move. If negative, it means starting from a position counted backward from the end.

  • whence：Optional, default value is 0. It defines a parameter for the offset, indicating which position to start the offset from; 0 means from the beginning of the file, 1 means from the current position, 2 means from the end of the file.

Return Value

If the operation succeeds, the new file position is returned. If the operation fails, the function returns -1.

Examples

The following examples demonstrate the use of the seek() method:

Examples

>>> f = open('workfile', 'rb+')
>>> f.write(b'0123456789abcdef')
16
>>> f.seek(5)      # Move to the sixth byte of the file
5
>>> f.read(1)
b'5'
>>> f.seek(-3, 2)  # Move to the third-to-last byte of the file
13
>>> f.read(1)
b'd'

The content of the file example.txt is as follows:

1:www.example.com
2:www.example.com
3:www.example.com
4:www.example.com
5:www.example.com

Read the file content in a loop:

Examples

#!/usr/bin/python3 # Open the file fo = open("example.txt", "r+") print ("File name:", fo.name) line = fo.readline() print ("The data read is: %s" % (line)) # Reset the file read pointer to the beginning fo.seek(0, 0) line = fo.readline() print ("The data read is: %s" % (line)) # Close the file fo.close()

The output of the above example is:

文件名为:  example.txt
读取的数据为: 1:www.example.com

读取的数据为: 1:www.example.com

Python3 File(文件) 方法Python3 File Methods

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