Convert integers to strings to create output filenames at run time

Question

I have a program in Fortran that saves the results to a file. At the moment I open the file using

OPEN (1, FILE = \'Output.TXT\')

However,

Answer 1

For a shorten version. If all the indices are smaller than 10, then use the following:

do i=0,9
   fid=100+i
   fname='OUTPUT'//NCHAR(i+48) //'.txt'
   open(fid, file=fname)
   !....
end do

For a general version:

character(len=5) :: charI
do i = 0,100
   fid = 100 + i
   write(charI,"(A)"), i
   fname ='OUTPUT' // trim(charI) // '.txt'
   open(fid, file=fname)
end do

That's all.