Reading exact line numbers from a file?

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David Pesetsky 2016-6-2

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https://ww2.mathworks.cn/matlabcentral/answers/287133-reading-exact-line-numbers-from-a-file

回答： Walter Roberson 2016-6-2

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Hi,

I'm using

C260=textscan(fid2, '%s', 1, 'delimiter', '\n', 'headerlines', 466-1);

...to read a specific line number. Now I realize if I want to read another specific line number, say 401, the pointer is in the wrong place, and Headers I think just advances it. Can I pinpoint any line number, in no specific order, and pull it out?

Thanks a lot, Dave

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Answer 1

Walter Roberson 2016-6-2

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textscan is always relative to the current position in the file. You can use fseek to rewind to the beginning of the file.

Positioning by line number is very inefficient. However if you are going to process a file multiple times then it can be effective to build an index of line numbers and corresponding offsets in the file which ftell can tell you.