How do I detect line number while reading a file?

Question

Clay Fulcher 2020-6-14

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/548229-how-do-i-detect-line-number-while-reading-a-file

评论： Clay Fulcher 2020-6-15

Is there a way to detect the line number while reading a text file? ftell will give a pointer in the file, but not the line number.

Thanks

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

per isakson 2020-6-15

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/548229-how-do-i-detect-line-number-while-reading-a-file#answer_451221

There is no function that takes the output of ftell() and returns the line number.

One has to keep track of the line number with user code. However, that is hard to combine with the use of fseek().

2 个评论
显示无隐藏无

Walter Roberson 2020-6-15

The I/O systems used by Windows, Mac, and Linux, do not keep track of the line number. Anything keeping track of the line number would have to be layered on top of the I/O system.

The situation is more tricky than it first appears, since repositioning is permitted, and since it is (generally speaking) permitted to write in the middle of a file (which can change the line numbering for anything after that point), and multiple processes can write into the same file.

Clay Fulcher 2020-6-15