plz check it if it is the correct way to do it.

Originally Posted by katharnakh

Hi,
Please go through this, before posting your code. Its not an assignment, just a prerequisite if you want to get really quick help.

Only with code it is hard to know what is working and what is not. Provide some input(example) details. Post your errors, if any OR if you are getting output, post it and explain, how you want it to be or how different it is from what you want.

katharnakh.

Originally Posted by prakasnisha

...
when i run this code, i m getting the file with the replaced values but the file is now containing only the new values, all the old data has been overwritten with the new one.and also i have hard coded it.is there any other way to do it? plz help me .

Originally Posted by prakasnisha

also i have hard coded it.is there any other way to do it?

Originally Posted by katharnakh

Hi,
First go through this.


Probably not. Because, from your code it is clear that you are opening your old_data1.txt in 'append'(from your code: open(OLD_DATA1,">>../nishap/nisha/old_data1.txt") or die("cant open the file $new"); ) mode. So, in the old_data1.txt file you should have original values + appended new modified values.

From the above statement it is clear that you are reading one file, doing some modification in the some line(keeping only modified lines in diff. scalars) and closing the file. Again opening the file in appending/output mode and rewriting those scalars which has you modified valuse back. The new values which get appended when you reopen the file in 'append' mode and write those scalar values.
The file should have only* those modified lines/scalar values in the file only when you open the file in output* mode *and* write only those scalar values. Because when you open a file in output mode, the contents of the file will get flushed first and new values are written. You can check this by simply opening file a file which has some data and closing it. You see the contents of the file flushed out without even you attempting to write something. Hope you got this.

What you should do?
In the program you read complete file into an array. Now each line of the file will be in one index of the array(i.e, $array[0] == <first line of the file>). Loop through the array, modify those specific values of array(nothing but, required lines of the file). Close the file and reopen file in OUTPUT mode and write array to the file.
For eg: The following program will comment out the same file living lines having only new-line character(means, im not modifying such lines).

Help with Code Tags

Perl Syntax (Toggle Plain Text)

# test.pl
use strict;
use warnings;
use FileHandle;
 
my $fh = FileHandle->new(".\\test.pl") || die "Cannot open file.";
my @lines = $fh->getlines();
$fh->close();
 
for my $i(0..$#lines){
	next if($lines[$i] =~ /^\s+$/);
	chomp($lines[$i]);
	$lines[$i] = $lines[$i] . '# CommentLine-' . eval($i+1) . "\n";
}
 
$fh = FileHandle->new("> .\\test.pl") || die "Cannot open file.";
$fh->print(@lines);
$fh->close();

# test.pl use strict; use warnings; use FileHandle; my $fh = FileHandle->new(".\\test.pl") || die "Cannot open file."; my @lines = $fh->getlines(); $fh->close(); for my $i(0..$#lines){ next if($lines[$i] =~ /^\s+$/); chomp($lines[$i]); $lines[$i] = $lines[$i] . '# CommentLine-' . eval($i+1) . "\n"; } $fh = FileHandle->new("> .\\test.pl") || die "Cannot open file."; $fh->print(@lines); $fh->close();

It is difficult to give you an idea how you should generalise. But i can tell you, list out distinct commands in your file and analyse the character sequence of it. Come to an approach how do you want to deal with those kind of lines when you encounter instead of hardcoding something.

katharnakh.