-----Original Message-----
From: Rob Dixon [mailto:[email protected]]
Sent: Thursday, March 17, 2011 10:37 AM
To: beginners
Cc: Chris Stinemetz
Subject: Re: input file
On 17/03/2011 15:56, Chris Stinemetz wrote:
>
> I'm trying to use file path for my file that I want to read but I am
> getting the following error when trying to use strict.
>
> Can't use string ("C://temp//PCMD") as a symbol ref while "strict
> refs" in use at ./DOband.pl line 10.
>
> Any help is greatly appreciated.
>
> #!/usr/bin/perl
>
> use warnings;
> use strict;
>
> my $filepath = "C://temp//PCMD";
You are getting confused with backward and forward slashes. Backward
slashes are the proper delimiter for Windows file paths, and require
escaping in strings with a second back slash. However Perl is kind and
allows either forward or backward slashes to serve the same purpose, but
a plain forward slash doesn't require escaping.
What you have written contains pairs of forward slashes which, luckily,
is interpreted the same as a single slash, so ultimately your code does
what it is supposed to.
You should either take advantage of Perl's leniency and write
my $filepath = "C:/temp/PCMD";
or use single quotes (within which backslashes need escaping only if
they appear as the final character) and write
my $filepath = 'C:\temp\PCMD';
> my $outfile = "output.txt";
>
>
> open ("$filepath") || die "ERROR: opening $filepath\n";
Except for old-fashioned and exotic syntax, a call to open requires
three parameters:
- The variable to assign the open file handle to
- The open mode (usually read or write)
- The file path and name
Apart from this, it is very wrong to enclose a simple scalar variable in
quotes. Doing so does have a purpose, but it is an esoteric one and is
almost never what you want to do.
It is best to stick to the low-priority 'or' instead of '||' as the
latter will do what you want only if you have put parentheses around the
parameters to the open call.
You should always put the system variable $! into your die string, as it
explains the reason for the failure. It is also a bad idea to terminate
the die string with a newline, as it prevents die from displaying the
source file and line number where the failure occurred.
Putting these together, your code should read
open my $fh, '<', $filepath or die "ERROR opening $filepath: $!";
> open (OUTFILE, "> $outfile") || die "ERROR: opening $outfile\n";
Interesting that you have remembered to include a file handle and an
open mode here! But the other points apply:
open my $outfile, '>', $outfile or die "ERROR opening $outfile: $!";
I hope this helps you.
Rob
Not sure what I am doing wrong but when I incorporate the infile that I want to
read and process the program does nothing and it seems like my PCMD file is
never opened.
Below is my code thus far.
Thank you,
Chris
#!/usr/bin/perl
use warnings;
use strict;
#my $filepath = 'PCMD';
my $filepath = 'C:/temp/PCMD';
my $outfile = 'output.txt';
open my $fh, '<', $filepath or die "ERROR opening $filepath: $!";
open my $out, '>', $outfile or die "ERROR opening $outfile: $!";
my @array;
while (<>) {
next unless /;/;
chomp;
my @data = ( split /;/ )[31,32,38,261];
push @array, join "\t", @data;
}
@array = sort {
my @aa = split /\t/, $a;
my @bb = split /\t/, $b;
$aa[0] <=> $bb[0] or
$aa[1] <=> $bb[1] or
$aa[2] <=> $bb[2];
} @array;
print $out "$_\n" foreach @array;
close $out;
#RTD 1 unit = 4 chips RUM Field 16 0 - 2^16 - 1 milliseconds
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