Python File truncate() Method

Overview

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

Syntax

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

fileObject.truncate( [ size ])

Parameters

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

Return Value

This method has no return value.

Example

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

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:

#!/usr/bin/python
# -*- coding: UTF-8 -*-

# 打开文件
fo = open("example.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 of the above example is:

文件名为:  example.txt
读取第一行: 1:www.example.com

读取数据:

The following example truncates the example.txt file to 10 bytes:

#!/usr/bin/python
# -*- coding: UTF-8 -*-

# 打开文件
fo = open("example.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()