next()方法当一个文件被用作迭代器，典型例子是在一个循环中被使用，next()方法被反复调用。此方法返回下一个输入行，或引发StopIteration异常EOF时被命中。

与其它文件的方法，如ReadLine()相结合next()方法工作不正常。然而，usingseek()将文件重新定位到一个绝对位置将刷新预读缓冲器。
语法

以下是next()方法的语法：

fileObject.next();

参数

NA

返回值

此方法返回下一个输入行。
例子

下面的示例演示next()方法的使用。

#!/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
 
for index in range(5):
  line = fo.next()
  print "Line No %d - %s" % (index, line)
 
# Close opend file
fo.close()

当我们运行上面的程序，它会产生以下结果：

Name of the file: foo.txt
Line No 0 - This is 1st line
 
Line No 1 - This is 2nd line
 
Line No 2 - This is 3rd line
 
Line No 3 - This is 4th line
 
Line No 4 - This is 5th line

来源：https://www.jb51.net/article/66628.htm