MATLAB: Get variable name into filename using strcat

chardoubleMATLABnumberstrcatvariable

I am trying to create a filename for a .csv file using an existing variable name, which is a number e.g. '5100', and a manual input, e.g. 'files'.
My code:
x=sum(A(:,2:end),2); %column vector containing the sum of each row (from columns 2:end)
short_files=A(find(x==0),1); %get datenum corresponding to each row of zeros
formatOut='yymmddHHMMSS'; %convert datenum back to original filename format
short_files=datestr(short_files, formatOut);  
filename_shortfiles=('short_files.csv'); %.csv filename
serialNo='5100';
%try to get serial no into filename :-S
%filename_shortfiles=strcat(serialNo,'short_files.csv'); %.csv filename
dlmwrite(fullfile(path,filename_shortfiles),short_files,'delimiter','');
Here, A is a matrix of data. Within that, I find the rows that contain zeros, and take the value in the first column of those particular rows. It is these values which I put in my output file that I am trying to write to a .csv file.
If I try 
filename_shortfiles=('short_files.csv');
…this works, but I would like to have part of the filename change on each iteration of the loop, depending on the value of serialNo.
The value of serialNo changes on each iteration of an earlier part of my code…
serialNo is a 1×1 double, is this the problem? I tried converting it using char() but this didn't work.
Thanks!

Best Answer

Nowhere do you describe/show what the output filename should look like, but this should get you started:
>> sno = 5100;
>> inp = 'short_files.csv';
>> [~,fnm,ext] = fileparts(inp);
>> out = sprintf('%s_%d%s',fnm,sno,ext)
out = short_files_5100.csv
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