How do I delete a specific line from a text file?
14 次查看(过去 30 天)
显示 更早的评论
Hi there guys,
I have a list of file locations that I have saved in a .txt file, all on new lines, like so:
C:\\User\Documents\file_name
C:\\User\Documents\file_name_2
C:\\User\Documents\file_name_3
C:\\User\Documents\file_name_4
I want to look through the file and see if the name in my .txt matches a predetermined name that I have previously chosen, and then delete it.
I can go through and find the one I want to delete with this code:
fileID = fopen('file_names.txt','wt');
num = length(importdata('Possiblelocs.txt');
for ii = 1:num
check = fgets(fileID(ii));
if check == new_str
'You found it!'
break;
else
continue;
end
end
However, I don't think this is a particularly good way of finding it, nor do I know how to delete the entire line when I have. Could anyone point me in the right direction? Thank you!
0 个评论
采纳的回答
dpb
2016-6-27
It's a sequential file so there isn't any way trivially to do what you want to the file itself. The right way would be to read the file, find the row in memory, delete it still in memory, then rewrite the file.
fileData=textread('file_names.txt','%s','delimiter','\n','whitespace','');
ix=~cellfun(@isempty,strfind(fileData,newstr));
fileData(ix)=[];
fid=fopen('file_names.txt','w');
for i=1:length(fileData)
fprintf(fid,'%s\n',fileData{i});
end
fid=fclose(fid);
6 个评论
dpb
2016-6-28
编辑:dpb
2016-6-28
I "don't do windows", so I'm certainly nobody to ask details re: GUI components, but isn't that only a function of the 'position' height? The 'String' property is what it is; there shouldn't be an empty full record and the linefeed shouldn't be in the string you display--mayhaps that's the problem; you're reading the lines including record terminators, not just the data???
Oh, and as for the "why?" question, the answer is that the final record doesn't have a record terminator and that is irregular. If you were to, say, append to the file you would have to prepend a newline before the first new record is written or it will simply be tacked onto the existing last record--unlikely what would be intended is just one example. Some applications will not correctly read the final record if it isn't terminated. It's "just not right" that way.
dpb
2016-6-29
"... an extra space at the end"
Oh, just dawned on me...certainly a blank line would show up, but that's not what speaking of when adding just the terminating \n. There should be no extra record unless it's in your original file and is simply being copied--if that's the case, clean up the original.
更多回答(0 个)
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Text Data Preparation 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!