How do I name a file from part of the file name read in?

I would like to read in files from a directory, store their names, modify the files, and write out new files with a name based on the files read in. I have a solution that takes the first 8 characters of the read in file and uses that as part of the new written file. But, I would like the code to take the part of the name before a specific character is observed (an underscore "_") because the number of characters changes depending on the samples I'm analyzing. The file I read in is named "6145abc_acquired.txt" and I would like to name the written file "6145abc-ave100raw.txt".

Here's part of my current code:

files = dir('*.txt');                   
numfiles = numel(files);                

              for i=1:length(files)                   
                  filename = files(i).name;          
                  [~,name] = fileparts(filename);     
                  nameaves = name(1:8);

                  ... in here I process the data creating the variable ave100...                

                  dlmwrite([nameaves, '-ave100raw' '.txt'], ave100, '\t');
              end

I would like to modify the name(1:8) to something that's more flexible and includes only what comes before the underscore "_".

Thanks.

Answer 1

[AJ von Alt]

The function strsplit will split a string into parts based on a delimiter.

Replace

nameaves = name(1:8);

With:

namesplit = strsplit( name , '_' );
nameaves = namesplit{1};

Answer 2

[Image Analyst]

Try this:

filename = '6145abc_acquired.txt'
underlineIndex = find(filename == '_', 1, 'first')
newFileName = sprintf('%s-ave100raw.txt', filename(1:underlineIndex-1))