python-3-文件-readline-方法

描述

方法readline()从文件中读取一整行。尾随的换行符保留在字符串中。如果大小参数存在且非负，则它是最大字节数，包括尾随换行符并且可能返回不完整的行。

仅当立即遇到 EOF 时才返回空字符串。

句法

以下是语法readline()方法 -


fileObject.readline( size );

参数

size− 这是要从文件中读取的字节数。

返回值

此方法返回从文件中读取的行。

例子

以下示例显示了 readline() 方法的用法。


Assuming that 'foo.txt' file contains following text:
This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line


#!/usr/bin/python3
# Open a file
fo = open("foo.txt", "r+")
print ("Name of the file: ", fo.name)
line = fo.readline()
print ("Read Line: %s" % (line))
line = fo.readline(5)
print ("Read Line: %s" % (line))
# Close opened file
fo.close()

结果

当我们运行上面的程序时，它会产生以下结果 -


Name of the file:  foo.txt
Read Line: This is 1st line
Read Line: This