File函数 中的 file.truncate([size])

Python file方法truncate()截断文件的大小。如果存在可选的size参数，文件将被截断为(至多)该大小。

大小默认为当前位置。当前文件位置不变。请注意，如果指定的size超过文件的当前大小，则输出取决于平台。

注意-如果文件以只读模式打开，此方法将不起作用。

file.truncate([size]) - 语法

fileObject.truncate( [ size ])

• size  -  如果存在此可选参数，文件将被截断为(至多)该大小。

file.truncate([size]) - 返回值

此方法不返回任何值。

链接：https://www.learnfk.comhttps://www.learnfk.com/python/file-truncate.html

来源：LearnFk无涯教程网

file.truncate([size]) - 示例

以下示例显示truncate()方法的用法。

This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

#!/usr/bin/python

# Open a file
fo=open("foo.txt", "rw+")
print "Name of the file: ", fo.name

# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line

line=fo.readline()
print "Read Line: %s" % (line)

# Now truncate remaining file.
fo.truncate()

# Try to read file now
line=fo.readline()
print "Read Line: %s" % (line)

# Close opend file
fo.close()

当无涯教程运行上面的程序时，它产生以下输出-

Name of the file:  foo.txt

Read Line: