To David Sanchez. Thank you very much for the answer. If you don't mind please elaborate it.

I use windows7. This is the place where I saved my data files. 'C:\Users\SRINATH KOMPELLA\Documents\MATLAB\Data. Inside the folder Data. Names of the data files are like this ioutput0257.dat , ioutput0462.dat, ioutput0488.dat, ioutput0645.dat, ioutput0798.dat, ioutput0825.dat. These are randomly picked examples. The actual files are named from 0001 to 0900. In each data file there are nx8 arrays (where n is a varying number of the order 1000). Of those,I have to pick up the 3th and 5th column as input for my program. You can also write to my mail. [e-mail]

Answer 1

[Iain]

 a = dir('C:\Users....\Data\*.dat');
 for i = 1:numel(a)
  filename = ['C:\Users...\Data\' a(i).name];
  ... code to read filename (you know the format)
  needed_data = read_data(:,[3 5]);
  ... code to pass the needed data to the program, or stack it in a matrix...
 end