drodinthe559 has asked for the wisdom of the Perl Monks concerning the following question:

Gurus, I pushing two columns binded together into an array. However, I am using substr instead of split. Is there a better way to do this? Below is the code I am using. 
open TRACE, "C:/test/trace_11122008.txt" or die "Couldn't open trace_1
+1122008.csv file: $!";

my @trace_row;

while (<TRACE>) {
    print chomp($_);
    push @trace_rw, {trace_cur =>
                        substr($_,0,10),
                        trace_orig =>
                        substr($_,11,18)};
}

[download]
Any suggestions would be greatly appreciated. Dave

Replies are listed 'Best First'.
Re: I need your opinion on pushing two columns into an array
by ccn (Vicar) on Nov 16, 2008 at 17:08 UTC 
    push @trace_rw, [unpack 'A10A8', $_] while <TRACE>;

    [download]

    or 

    my @trace_rw = map { [unpack 'A10A8', $_] } <TRACE>;

    [download]
[reply]
[d/l]
[select]
      Thanks. What I'm try to do is search a text file for certain numbers and if it finds it in the array to replace it. The problem I'm now having is in my if statement. The $stmt_tr keeps on changing to the array variable when it should keep the number I'm trying to find in the array. 
      while (<CIPA>) {
    my $string = $_;
    my $stmt_tr = substr($_,126,10);
        if ((substr($string,126,1) =~ m/5/) && (substr($string,98,8) =
+~ m/20081112/)) {
            foreach my $x (@trace_row) {
                if ($stmt_tr = $x->{trace_orig}) {
                    print $x->{trace_orig} . "\n";
                
                }
            }
            print $string;
            ++$rcount;
            print $rcount . "\n";
        }
    }

      [download]
[reply]
[d/l]
        if ($stmt_tr = $x->{trace_orig}) { is an assigment

        use
        if ($stmt_tr == $x->{trace_orig}) { 'double =' for numbers
        if ($stmt_tr eq $x->{trace_orig}) { 'eq' for strings

[reply]
[d/l]
[select]
        while (<CIPA>) {
    my $string = $_;
    my $stmt_tr = substr($_,126,10);
        if ((substr($string,126,1) =~ m/5/) && (substr($string,98,8) =
+~ m/20081112/)) {

        [download]

        That should be: 

        while ( my $string = <CIPA> ) {
    my $stmt_tr = substr $string, 126, 10;
        if ( substr( $string, 126, 1 ) == 5 && substr( $string, 98, 8 
+) == 20081112 ) {

        [download]
[reply]
[d/l]
[select]
        I found the cheesy mistake that is make that happen "=". I should be using "=~".
[reply]
Re: I need your opinion on pushing two columns into an array
by GrandFather (Saint) on Nov 16, 2008 at 20:04 UTC

    print chomp($_); probably isn't doing what you expect. chomp returns the number of characters it removed so most likely your print simply generates a long string of ones.

    I notice that the file has a .csv extension which implies a CSV file. Generally it is a bad idea to hand parse CSV because there are a number of quite nasty edge cases to deal with. You may resolve many of you problems by using Text::CSV or Text::xSV.

    Perl reduces RSI - it saves typing
[reply]
[d/l]
Re: I need your opinion on pushing two columns into an array
by Anonymous Monk on Nov 16, 2008 at 17:02 UTC
    Depends on what you're doing ... but you could 
    push @trace_rw, [ substr($_,0,10), substr($_,0,18) ];

...
$trace_rw[0][0];
$trace_rw[0][1];
...

use constant TRACE_CUR => 0;
use constant TRACE_ORIG => 1;
$trace_rw[0][TRACE_CUR];
$trace_rw[0][TRACE_ORIG];

    [download]
    to save a little on memory/speed
[reply]
[d/l]

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