How to make a variable content part of a path

I have a string variable, which is changing during the loop, it is named filename and it takes on values like 'file001.txt', 'file002.txt'... I am saving the files 'file001.txt', 'file002.txt' in a loop and would like to call the filename variable

>> fid_out = fopen('/Users/Y*****/Downloads/case_data/train2/3/"filename"', 'w'); at the place "filename", I would like it to be 'file001.txt', 'file002.txt'...... how can I realize that?

Answer 1

[KL]

filepath = '/Users/Y*****/Downloads/case_data/train2/3';
filename = 'file001.txt';

and then use fullfile

fid_out = fopen(fillfile(filepath,filename));

https://www.mathworks.com/help/matlab/ref/fullfile.html

if you store your filenames in a cell array,

 filenames  {'file001.txt', 'file002.txt'};

then it's even better inside a loop

 for fno = 1:numel(filenames)
    fid_out{fno} = fopen(fillfile(filepath,filename{fno}));
    %something
 end

[TingTing]

Thank you so much. This works. Just an extra question. If I have i = 1,2,3,4... and want this i to be part of the path itself, i.e.,

/Users/Y*****/Downloads/case_data/train2/1' /Users/Y*****/Downloads/case_data/train2/2' /Users/Y*****/Downloads/case_data/train2/3'

What shall I do?

[KL]

Just the same idea,

 path_part1 = '/Users/Y*****/Downloads/case_data/train2';
 path_part2 = {'1', '2', '3'};
 filenames = {'file001.txt', 'file002.txt'};

then

 fullfile(path_part1,path_part2{1},filenames{1})