MATLAB: Accesing files with different names

accessing files

I have 2000 files each with a different name in the pattern: data_23.575_43.475 (i.e. data_number 1_number2)
Each file has time series data. I want to add values present in the 4th column corresponding to the dates (present in the first. second and third column) from each file. How can I do so?