What is the Python File truncate() method? Where can it be used?

Today in this article we will learn about the truncate method in python. We may not know truncate usage before entering the article, but in this article We will use truncate statement examples to let you understand the truncate method in today's article.

Overview

The truncate() method is used to truncate the file. If the optional parameter size is specified, it means the file is truncated to size characters. If size is not specified, it is truncated from the current position; after truncation, all characters following size are deleted.

Syntax

##The truncate() method syntax is as follows:

fileObject.truncate( [ size ])

Parameters

size -- Optional, if present, the file is truncated to size bytes.

(This method has no return value.)

Example

The following example demonstrates the use of the truncate() method:

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

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

Loop to read the content of the file:

#!/usr/bin/python
# -*- coding: UTF-8 -*-
# 打开文件
fo = open("runoob.txt", "r+")
print "文件名为: ", fo.name
line = fo.readline()
print "读取第一行: %s" % (line)
# 截断剩下的字符串
fo.truncate()
# 尝试再次读取数据
line = fo.readline()
print "读取数据: %s" % (line)
# 关闭文件
fo.close()

The output result of the above example is:

文件名为:  runoob.txt
读取第一行: 1:www.runoob.com
读取数据:

The following example intercepts runoob. 10 bytes of txt file:

#!/usr/bin/python
# -*- coding: UTF-8 -*-
# 打开文件
fo = open("runoob.txt", "r+")
print "文件名为: ", fo.name
# 截取10个字节
fo.truncate(10)
str = fo.read()
print "读取数据: %s" % (str)
# 关闭文件
fo.close()

The output result of the above example is:

文件名为:  runoob.txt
读取数据: 1:www.runo

In this article, we explain what the truncate() method is. If you don’t understand, you can Give it a try. After all, hands-on practice is the best way to verify what you have learned. Finally, I hope this article can bring some help to you who are learning python.

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