Solved

How can I delete first 15 lines in a text file

Posted on 1999-01-11
8
175 Views
Last Modified: 2010-05-03
I am using file to write log details. I want the size of the file to be less than 15k. So when ever it exceeds 15k i want to delete the oldest data. How can I delete the old data leaving the latest data. I am writing to the file with append mode.
0
Comment
Question by:lesa
  • 5
  • 2
8 Comments
 
LVL 2

Accepted Solution

by:
VBDesigns earned 10 total points
ID: 1455543
If it's a text file, this way should work:

Dim iFF as Integer
Dim lLength as Long
CONST MAX_FILE_LEN = 15000
Dim sValue as String * MAX_FILE_LEN

iFF = FreeFile

Open "c:\textfile.txt" for binary as #iFF
lLength = LOG (#iFF)
if lLength > MAX_FILE_LEN then
   Seek(#iFF), (lLength - MAX_FILE_LEN)
   Get #iFF, , sValue
endif

Close #iFF

Kill "c:\textfile.txt"

Open "c:\textfile.txt" for Binaryt as #iFF
Put #iFF, , sValue
Close # iFF
0
 

Author Comment

by:lesa
ID: 1455544
I want the oldest data to be deleted means the top data in the file because as I am using the append method latest will be at bottom. So plese let me know how can I do it.
0
 

Author Comment

by:lesa
ID: 1455545
I want the oldest data to be deleted means the top data in the file because as I am using the append method latest will be at bottom. So plese let me know how can I do it.
0
Problems using Powershell and Active Directory?

Managing Active Directory does not always have to be complicated.  If you are spending more time trying instead of doing, then it's time to look at something else. For nearly 20 years, AD admins around the world have used one tool for day-to-day AD management: Hyena. Discover why

 

Author Comment

by:lesa
ID: 1455546
I want the oldest data to be deleted means the top data in the file because as I am using the append method latest will be at bottom. So plese let me know how can I do it.
0
 

Author Comment

by:lesa
ID: 1455547
I want the oldest data to be deleted means the top data in the file because as I am using the append method latest will be at bottom. So plese let me know how can I do it.
0
 

Author Comment

by:lesa
ID: 1455548
I want the oldest data to be deleted means the top data in the file because as I am using the append method latest will be at bottom. So plese let me know how can I do it.
0
 
LVL 3

Expert Comment

by:vikiing
ID: 1455549
As the file you're working with is a sequential (text) one, the only thing you can do is:
a) Load file lines into an array (a vector), and calculate how many lines it has
b) Destroy original file and re-create a newer one, starting with line #n (where "n" depends on the amount of data you want to get rid of).

Code can be something like this:

Dim TextLines$(30000) : F%=FreeFile
Open <file> for input as F% : LC%=0
Do Until EOF(F%)
   LC%=LC%+1 : Line Input #F%,TextLines$(LC%)
Loop

Close #F% : Open <file> for output as #F%
For I%=N% to LC%   <==== Read below ====>
   Print #F%,TextLines$(I%)
Next I%

The value N% at For instruction, specifies which is the first line you want to keep in the file (toghether from there downwards). Doing so, you're chopping the first N%-1 lines.

Perhaps you want to chop the file in order its final size be EXACTLY 15 Kb. In that case, value N% must be found counting lengths of lines, this way:

FullSize%=LOF(F%) : N%=0
Do
   N%=N%+1 : FullSize%=FullSize%-Len(TextLines$(N%))-2
Loop Until FullSize%<=15360   '15360 = 15 * 1024 = 15 Kb

When FullSize% reaches 15K, N% will have the first line from which the rest of the file will fit into that size.


0
 
LVL 3

Expert Comment

by:vikiing
ID: 1455550
I had a mess with "15k" and "15 lines". In the code I've posted, write out the For as

     For I%=16 to LC%

and forget the portion below (because N%=16, and doesn't need to be calculated)
0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Introduction In a recent article (http://www.experts-exchange.com/A_7811-A-Better-Concatenate-Function.html) for the Excel community, I showed an improved version of the Excel Concatenate() function.  While writing that article I realized that no o…
If you need to start windows update installation remotely or as a scheduled task you will find this very helpful.
Get people started with the process of using Access VBA to control Excel using automation, Microsoft Access can control other applications. An example is the ability to programmatically talk to Excel. Using automation, an Access application can laun…
Get people started with the utilization of class modules. Class modules can be a powerful tool in Microsoft Access. They allow you to create self-contained objects that encapsulate functionality. They can easily hide the complexity of a process from…

803 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question