描述

统计文件行数

问题 Problem

需要计算文件的行数

解决 Solution

The simplest approach, for reasonably sized files, is to read the file as a list of lines so that the count of lines is the length of the list.

对于具有适当大小的文件，最简单方法是拷贝文件各行到一个list中，list的长度就是文件的行数。

If the file's path is in a string bound to the thefilepath variable, that's just:

如果文件路径由下面的string变量thefilepath给出，代码如下：

count = len(open(thefilepath).readlines(  ))

For a truly huge file, this may be very slow or even fail to work. If you have to worry about humongous files, a loop using the xreadlines method always works:

对于很大的文件，readlines可能很慢，甚至操作失败。如果需要处理特别巨大的文件，使用xreadlines函数的循环可以保证不会出问题：

count = 0
for line in open(thefilepath).xreadlines(  ): count += 1

Here's a slightly tricky alternative, if the line terminator is '\n' (or has '\n' as a substring, as happens on Windows):

如果行分隔符号是'\n'(Windows中'\n'作为一个子串出现)，那么可以选用如下的小技巧：

count = 0
thefile = open(thefilepath, ''''rb'''')
while 1:
    buffer = thefile.read(8192*1024)
    if not buffer: break
    count += buffer.count('\n')
thefile.close(  )

Without the 'rb' argument to open, this will work anywhere, but performance may suffer greatly on Windows or Macintosh platforms.

如果不使用上面的rb参数，脚本也会正常工作，但是在Windows或Macintosh平台上可能有很大的效率损失。

讨论 Discussion

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PyCkBk-4-7

描述

问题 Problem

解决 Solution

讨论 Discussion

参考 See Also