Hi, I am a new IDL user. For the purposes of my work I need to read a large number of binary files in a loop and then save them as ascii files. I was hoping you could help me with that. The program that I am using can only read one file at a time 'fpname' and then spit out 4 output variables on the screen: swdnsrf,lwdnsrf,swupsrf,lwupsrf. To execute the code I run the command: read_fluxes, './app_n025_2011350_1400.SurfFluxes',swdnsrf, lwdnsrf, swupsrf, lwupsrf where ' app_n025_2011350_1400.SurfFluxes' is the file that I am trying to read, and swdnsrf, lwdnsrf, swupsrf, lwupsrf are the variables coming from that file. Now, I need to modify the code so it would read the whole cluster of files for other time steps "j", where j goes from 001,350 app_n025_2011"j"_1400.SurfFluxes Could you please look at my program below that works for reading one file and writing 4 variables on the screen and suggest how it needs to be modified to output ascii files and read many files in a do loop? Thanks pro read_fluxes, fpname, swdnsrf,lwdnsrf,swupsrf,lwupsrf ; Input: ; fpname: Input file full path name, string, e.g. 'app_n025_2011161_1400.SurfFluxes'. ; ; Output: ; swdnsrf: Downwelling shortwave radiation at the surface (W/m^2) ; lwdnsrf: Downwelling longwave radiation at the surface (W/m^2) ; swupsrf: Upwelling shortwave radiation at the surface (W/m^2) ; lwupsrf: Upwelling longwave radiation at the surface (W/m^2) ; openr, uin, fpname, /get_lun ncols= fix(0) nrows=fix(0) readu,uin,ncols, nrows swdnsrf = fltarr(ncols,nrows) lwdnsrf = fltarr(ncols,nrows) swupsrf = fltarr(ncols,nrows) lwupsrf = fltarr(ncols,nrows) readu,uin,swdnsrf readu,uin,lwdnsrf readu,uin,swupsrf readu,uin,lwupsrf close,uin & free_lun,uin end