×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Position pointer in I/O

Position pointer in I/O

Position pointer in I/O

(OP)
Hi all,

When you read data from a data file (txt file), how can you move the position pointer to the n row of the data (without reading each row again and again)?
For I am writing a program to put the n row of the data into an array, I am currently repeating
read (101,*)
n-1 times to get rid of the data I don't need, but that is inefficient, isn't it?
Thanks in advance.  

RE: Position pointer in I/O

If Fortran, those two choices of reading a file are called:

Sequential access, and
Direct access

You may read a bit on it anywhere, here are 3 links.
http://docs.cray.com/books/S-3695-35/html-S-3695-35/b8umksmg.html
http://rsusu1.rnd.runnet.ru/develop/fortran/prof77/node162.html
http://frateralphio.wordpress.com/2010/11/06/fortran-and-binary-files-sequential-access/

I personally have not used Direct access much. I usually think of it for reading huge binary files; which I have no need for.

Read the links above carefully, for Direct access apparently the records in the file all need to be of the same length.
 

RE: Position pointer in I/O

Why not just use two files.  Read from one, write the data you want to the other.  When you have finished, delete the original and rename the new file to the original.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources