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#1
February 13th, 2001, 12:18 PM
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Hi
I am using a flat file (e.g info.txt) to retrieve data. i want to get the input from a text field of form (for e.g say name) .i want to delete and modify a particular record by using the name from form input. i have used tab for seperating the fields of the record in the text file. Can anyone help me how to do that? Thanks in Advance Keshav
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#2
February 13th, 2001, 01:00 PM
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You could use some conditional statements and push the records you want to keep onto an array. Then print that array to a new file. If you do it correctly in the logic you shouldn't have to worry about deleting the old file either.
__________________
- dsb -  Perl Guy
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#4
February 13th, 2001, 01:34 PM
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Are you trying to learn Perl? Or are you just trying to use it to get this done?
If you are trying to learn Perl then I'd suggest you try it yourself first. I'd be glad to help you along the way( feel free to email me ), but I think you'd learn better if you took a crack at it before I give you the code.  Not to be a pain in the ***, but you'll understand it better if you find your own way there.  I will help you though.
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#5
February 13th, 2001, 01:55 PM
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hi
Hi dsb,
Thanks for your immediate response. I am learning and also it should be get done. I had tried to work it. But its not working. I have given my code below. Please check it out and make it work. Thanks Keshav #!/usr/bin/perl use CGI; print"content-type:text/html\n\n"; my $action = new CGI; my $username = $action->param('username'); my $file = "members.txt"; my $old = $file; my $new = "$file.tmp.$$"; my $bak = "$file.bak"; $found = undef; open(OLD, "< $old") or die "can't open $old: $!"; open(NEW, "> $new") or die "can't open $new: $!"; @data = <OLD>; close (OLD); LOOP: foreach $row(@data){ #my $row = $_; chomp($row); #my @currentrow = (); @currentrow = split(/\t/, $row); #$currentrow = @currentrow; if ($username eq $currentrow[0]){ $found = 1; last LOOP; } } if (defined($found)) { push @currentrow; exit; } close(OLD) or die "can't close $old: $!"; close(NEW) or die "can't close $new: $!"; rename($old, $bak) or die "can't rename $old to $bak: $!"; rename($new, $old) or die "can't rename $new to $old: $!"; else { print "invalid name"; exit; }
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#6
February 13th, 2001, 02:07 PM
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All right, for the sake of time, I'll give you an example of what I need and then you can incorporate where you need it. I'll comment it to explain what I'm doing.
Code:
open( OLD, "filename.txt" ) || die "no!\n"; # you don't need the arrows to signify readability it will default to read in
while ( <OLD> ) {
chomp; # get read of the newline at the end of the line
# here you would put the code
# that determines whether or not
# you want to keep that line
if ( <condition to determine keeping> ) {
# to keep
push( @lines, $_ );
} else {
next; # will go on to next line - no need to do anything else
}
}
close(OLD);
open( NEW, ">filename.txt" ) || die "no!\n"; # using same filename will overwrite old file so you won't need to delete it later
foreach $n ( 0 .. $#lines ) { # loop to print array of lines to new file
print NEW $lines[$n], "\n";
}
close(NEW);
I didn't try this code so you may need to tweak it a little bit. I'll help anywhere I can, but make sure you understand what's going on here. Hope this Helps!
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#8
February 13th, 2001, 04:07 PM
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I didn't do any record manipulation in my code. If things are getting deleted the problem is in your code.
I took a look at your code and I saw that when you try to push onto '@currentrow' you don't specify an argument to push onto the array. Look into that. Hope that helps.
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#9
February 13th, 2001, 04:10 PM
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Hi,
You don't see the old code. Here is the new one. Check it and reply me. thanks Keshav #!/usr/bin/perl use CGI; print"content-type:text/html\n\n"; my $action = new CGI; my $username = $action->param('username'); my $file = "members.txt"; my $old = $file; open(OLD, "< $old") or die "can't open $old: $!"; while (<OLD>) { my $nowRow = $_; chomp($nowRow); my @currentRow = (); @currentRow = split(/\t/, $nowRow); if ($username eq $currentrow[0]){ push( @currentRow, $nowRow ); } else { next; # will go on to next line } } close(OLD); open( NEW, ">members.txt" ) || die "no!\n"; foreach $n ( 0 .. $#lines ) { # loop to print array of lines to new file print NEW $lines[$n], "\n"; } close(NEW);
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#10
February 13th, 2001, 04:17 PM
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In this section, where you write to a new file: Code:
open( NEW, ">members.txt" ) || die "no!\n";
foreach $n ( 0 .. $#lines ) { # loop to print array of lines to new file
print NEW $lines[$n], "\n";
}
close(NEW);
Replace every instance of 'lines' with the name of your array which i believe is currentRow. So it will look like this: Code:
open( NEW, ">members.txt" ) || die "no!\n";
foreach $n ( 0 .. $#currentRow ) { # loop to print array of lines to new file
print NEW $currentRow[$n], "\n";
}
close(NEW);
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#13
February 13th, 2001, 04:57 PM
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Hi
Yes $username is correct. I am able to get that parameter and able to print it. I checked it by print $username;. But still its not working i don't know why. pls help me. Keshav
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#15
February 13th, 2001, 05:05 PM
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No Colon is not there. I have given the source below. Pls check it line by line and reply me.
Keshav #!/usr/bin/perl use CGI; print"content-type:text/html\n\n"; my $action = new CGI; my $username = $action->param('username'); open(OLD, "members.txt") or die "can't open $old: $!"; while (<OLD>) { my $nowRow = $_; chomp($nowRow); my @currentRow = (); @currentRow = split(/\t/, $nowRow); if ($username eq $currentrow[0]){ push( @currentRow, $nowRow ); } else { next; # will go on to next line } } close(OLD); open( NEW, ">members.txt" ) || die "no!\n"; foreach $n ( 0 .. $#currentRow ) { # loop to print array of lines to new file print NEW $currentRow[$n], "\n"; } close(NEW);
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