print to screen but blank to file!?!

[jggrossm]

Hi all. I'm new at perl. Just using it to strip some fields of a comma-delimited file. This code works when printing to the screen, but not to a file. Any help would be much appreciated.

#!/usr/bin/perl -w

#STRIPS last 5 fields off a comma-delimited file

#OPENS FILE
open (DI, ">DIAMOND20070126.txt") or die "I couldn't get at it";

# GRABS LINE
for $line(<DI>) {

# TOKENIZES LINE
@tokenized = split(/,/,$line);

# POPS END FIELDS OFF
for $i (17 .. 21){
pop(@tokenized);
}

#PUSHES REMAINING FIELDS INTO NEW ARRAY
@joined = join(',',@tokenized);
push(@trimmed,@joined);

}
#WRITES NEW ARRAY TO FILE
for $i (1 .. 20) {
print DI "@trimmed[$i]\n";
}
close DI;

 

[KevinADC]

the main problem is you opened the file in write/create mode '>'.

This should do what you want:

[gray]#!/usr/bin/perl  -w[/gray]
[url=http://perldoc.perl.org/functions/use.html][black][b]use[/b][/black][/url] [green]strict[/green][red];[/red]
[url=http://perldoc.perl.org/functions/my.html][black][b]my[/b][/black][/url] [blue]@trimeed[/blue] = [red]([/red][red])[/red][red];[/red]
[url=http://perldoc.perl.org/functions/open.html][black][b]open[/b][/black][/url] [red]([/red]IN, [red]"[/red][purple]<DIAMOND20070126.txt[/purple][red]"[/red][red])[/red] or  [url=http://perldoc.perl.org/functions/die.html][black][b]die[/b][/black][/url] [red]"[/red][purple]I couldn't get at it: [blue]$![/blue][/purple][red]"[/red][red];[/red]
[olive][b]while[/b][/olive] [red]([/red]<IN>[red])[/red] [red]{[/red]
   [url=http://perldoc.perl.org/functions/push.html][black][b]push[/b][/black][/url] [blue]@trimeed[/blue], [url=http://perldoc.perl.org/functions/join.html][black][b]join[/b][/black][/url] [red]'[/red][purple],[/purple][red]'[/red], [red]([/red][url=http://perldoc.perl.org/functions/split.html][black][b]split[/b][/black][/url][red]([/red][red]/[/red][purple],[/purple][red]/[/red],[blue]$_[/blue][red])[/red][red])[/red][red][[/red][fuchsia]0..16[/fuchsia][red]][/red][red];[/red]
[red]}[/red]
[url=http://perldoc.perl.org/functions/close.html][black][b]close[/b][/black][/url] IN[red];[/red]
[black][b]open[/b][/black] [red]([/red]OUT, [red]"[/red][purple]>DIAMOND20070126.txt[/purple][red]"[/red][red])[/red] or  [black][b]die[/b][/black] [red]"[/red][purple]I couldn't get at it: [blue]$![/blue][/purple][red]"[/red][red];[/red]
[url=http://perldoc.perl.org/functions/print.html][black][b]print[/b][/black][/url] OUT [red]"[/red][purple][blue]$_[/blue][purple][b]\n[/b][/purple][/purple][red]"[/red] [olive][b]for[/b][/olive] [blue]@trimeed[/blue][red];[/red]
[black][b]close[/b][/black] OUT[red];[/red]

Pragmas (perl 5.8.8) used :
[ul]
[li]strict - Perl pragma to restrict unsafe constructs[/li]
[/ul]

------------------------------------------
- Kevin, perl coder unexceptional!

 

[jggrossm]

Wow - your code worked. Thanks! But I'd still like to understand why mine didn't. I tried switching '>' to '<' and got:
Filehandle DI opened only for input at stripsDI_extraFieds.pl line 31, <DI> line 35.

 

[KevinADC]

you can only read '<' or write '>' to a filehandle using those operators, but not both at the same time. There is '+<' for read/write access but it's buggy and seems to be platform dependent so I never use it. You could use perls in-place editor for this task. Untested code:

[gray]#!/usr/bin/perl  -w[/gray]
[url=http://perldoc.perl.org/functions/use.html][black][b]use[/b][/black][/url] [green]strict[/green][red];[/red]
[red]{[/red]
   [url=http://perldoc.perl.org/functions/local.html][black][b]local[/b][/black][/url] [blue]@ARGV[/blue] = [red]([/red][red]'[/red][purple]DIAMOND20070126.txt[/purple][red]'[/red][red])[/red][red];[/red]
   [black][b]local[/b][/black] [blue]$^I[/blue] = [red]'[/red][purple].bac[/purple][red]'[/red][red];[/red]
   [olive][b]while[/b][/olive] [red]([/red]<>[red])[/red] [red]{[/red]
      [url=http://perldoc.perl.org/functions/chomp.html][black][b]chomp[/b][/black][/url][red];[/red]
      [url=http://perldoc.perl.org/functions/print.html][black][b]print[/b][/black][/url] [url=http://perldoc.perl.org/functions/join.html][black][b]join[/b][/black][/url] [red]'[/red][purple],[/purple][red]'[/red], [red]([/red][url=http://perldoc.perl.org/functions/split.html][black][b]split[/b][/black][/url][red]([/red][red]/[/red][purple],[/purple][red]/[/red],[blue]$_[/blue][red])[/red][red])[/red][red][[/red][fuchsia]0..16[/fuchsia][red]][/red],[red]"[/red][purple][purple][b]\n[/b][/purple][/purple][red]"[/red][red];[/red]
   [red]}[/red]
[red]}[/red]

------------------------------------------
- Kevin, perl coder unexceptional!

 

[jggrossm]

Whoa - your signature clearly rings true.

Okay, take pity on me and explain one more part to me. Where's the pop?

 

[KevinADC]

don't need to use pop(). I used an array slice that only returns the parts of the array you want to begin with:

(split(/,/,$_))[b][0..16][/b]

that does what you did here:

    @tokenized = split(/,/,$line);

    # POPS END FIELDS OFF
    for $i (17 .. 21){
        pop(@tokenized);
    }

but without using a temporary variable - @tokenized - to hold the data. Instead it's sent directly to the join() function to be reassembled "on the fly".


------------------------------------------
- Kevin, perl coder unexceptional!