Login or Register to Ask a Question and Join Our Community


Programming

Jumping to a particular line in a file

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums Programming Jumping to a particular line in a file
# 1  
Old 06-07-2010
Question Jumping to a particular line in a file
Hi,

I have an output file which has more than 1,000,000,000 lines. I am accessing this file in another C++ program. Now while accessing the output file using cin, I want to jump, say, to the 5,000,000th line directly and start accessing data from there. Is this possible? Could someone please give me a small C++ code for the same?

Thanks in advance!
# 2  
Old 06-07-2010
Unless all of the records are the same indentical lengths you cannot do that.

To move the file pointer check out fseek(), lseek(), fsetpos().
# 3  
Old 06-07-2010
Yes, all the records are of the same identical lenghts. However, doesnt fseek() seek on the basis of the no. of bytes? Are you suggesting that i find out the size (in bytes) of each line and then mutiply it with the line no. of the particular line that I want to access?
# 4  
Old 06-08-2010
Exactly - that is how you do random access in a file.
# 5  
Old 06-08-2010
Quote:
Originally Posted by mugga
Yes, all the records are of the same identical lenghts. However, doesnt fseek() seek on the basis of the no. of bytes? Are you suggesting that i find out the size (in bytes) of each line and then mutiply it with the line no. of the particular line that I want to access?
If the file contains variable size lines then you can count the newlines in the input...so to jump to the 100th line you would need to count 99 newlines. But if the lines are all of equal length then jim's method is the best.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Bash script jumping too quickly to the next command - crash

Hi, (I am not too good in command-lines). I am running a bash script and at some point my loop starts to run super quickly. Then, the steps after do not get processed and there is no further outpout generated. I tried with the sleep 20s option, as I thought some steps would get overlapped, but... (22 Replies)
Discussion started by: tremblayemilie9
22 Replies

2. Shell Programming and Scripting

Need a program that read a file line by line and prints out lines 1, 2 & 3 after an empty line...

Hello, I need a program that read a file line by line and prints out lines 1, 2 & 3 after an empty line... An example of entries in the file would be: SRVXPAPI001 ERRO JUN24 07:28:34 1775 REASON= 0000, PROCID= #E506 #1065: TPCIPPR, INDEX= 003F ... (8 Replies)
Discussion started by: Ferocci
8 Replies

3. Shell Programming and Scripting

Read file line by line and process the line to generate another file

Hi, i have file which contains data as below(Only sample shown, it may contain more data similar to the one shown here) i need to read this file line by line and generate an output file like the one below i.e based on N value the number of MSISDNs will vary, if N=1 then the following... (14 Replies)
Discussion started by: aemunathan
14 Replies

4. Solaris

jumping from one line to another

Hi, Thanks (10 Replies)
Discussion started by: rocky1954
10 Replies

5. BSD

Jumping from Solaris to BSD?

Hi all, I currently run an OpenSolaris (b134) server at home for share media between a few computers (all Macs at the moment). I use ZFS to mirror a couple of disks and have a couple of SMF manifests. My background is as a user of OS X and as a user of (Open)Solaris with formal training in... (7 Replies)
Discussion started by: forquare
7 Replies

6. Shell Programming and Scripting

[Solved] Problem in reading a file line by line till it reaches a white line

So, I want to read line-by-line a text file with unknown number of files.... So: a=1 b=1 while ; do b=`sed -n '$ap' test` a=`expr $a + 1` $here do something with b etc done the problem is that sed does not seem to recognise the $a, even when trying sed -n ' $a p' So, I cannot read... (3 Replies)
Discussion started by: hakermania
3 Replies

7. Shell Programming and Scripting

work area directory jumping script?

hi all, Ive been trying to find some way of doing this for ages but i have is a shell script that activates a python search and there it no tab completion. more familliar with tcsh at the moment but i'm a newbe. i was trying to make an easy way to browse to a list of working directories. ... (0 Replies)
Discussion started by: jvan
0 Replies

8. Shell Programming and Scripting

script to loop and check jumping seq.

Hi, Normally, I will manually to use "ll" command to list the following file from \FILE\CACHE\ directory and check the jump seq. Can I write a script to loop or/and check jump seq file (if jumped seq and show "missing seq no" message for me) -rw-rw----+ 1 user develop 14012 Sep 4... (1 Reply)
Discussion started by: happyv
1 Replies

9. Programming

jumping to a specific line in a text file

hi everybody! i need to read a specific line from a text file using C. can any one suggest how to do it. i m aware abt fread(), fwrite(), fseek()... but using these allows the pointer to be moved 1 character at a time. Is there a way i could jump directly to a line if i know the line number?... (4 Replies)
Discussion started by: mridula
4 Replies

10. Shell Programming and Scripting

Jumping to next line with awk

I am defining an awk function (Solaris v8 ksh) of: function firstletter { echo "$line" | awk '{get=substr($1,1,1);print get}' | read FL } I am starting a wile loop with a: for line in `cat inputfile.lst` When I call the function from within the for loop it works great fine. From within... (4 Replies)
Discussion started by: gozer13
4 Replies
Login or Register to Ask a Question