Hi Rudic

Thank you so much for answering! I almost solved my problem but stuck in one single step. I have to read 10000 files which are named as

Code:

OwZ-1.xyz, OwZ-10.xyz, OwZ-10000.xyz

like this.
The problem is when I read files like this-

Code:

 do i=1,9    ! file loop
          write(filename,100)i
          100 format('OwZ-',I1,'.xyz')

it can read only upto 9 files. To read from to 10 to 99 I have to make that I2! I tried adding 0's on the left like

Code:

OwZ-00001.xyz,OwZ-00002.xyz

but then when I say

Code:

do i=1,9    ! file loop
          write(filename,100)i
          100 format('OwZ-',I5.5,'.xyz')

it can't read those files!!

How do I read all files from 1 to 10000?

Thanks! Really appreciate it!

Saleheen