..... ..... ....  ....  ....
..... ..... ....  ....  ....
total 1234  1234  5678  7894
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#!/usr/local/bin/perl -w
my($currentLine, $name, $infilename);
chomp ($infilename = "temp1.pl");
    if ($ currentLine =~ /^ \$name:/) {
        print $currentLine;
}
[download]

It sounds like you just want a simple script to open a file, find the line that says "total", and report the last two rows of numbers. Here is some code to do this :

#!/usr/local/bin/perl

print "Input file name: ";
$_ = <>;
chop;
open(INFILE, $_);
while (<INFILE>)
{
        if (m/total/)
        {
                s/^total\s[0-9]+\s[0-9]+\s([0-9]+)\s([0-9]+)$/$1 $2/;
                print;
        }
}
close INFILE;
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There are probably 3 things in this script that are non-intuitive to the budding Perl programmer :

1) The use of $_
2) The use of <>
3) The use of regular expressions

Here they are, demystified :

1) $_ is the "default variable" when you don't supply any other variable name to a sub (such as chop and print in our example).

2) <> abbreviates <STDIN>

3) There are two regular expressions in this example, the first one is a matching regular expression (m/total/) which returns true if and only if the text "total" exists as a substring of $_

The second regular expression is a search and replace regex.


s/^total\s[0-9]+\s[0-9]+\s([0-9]+)\s([0-9]+)$/$1 $2/
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all it does is replace "^total\sA\sB\sC\sD$" with "C D" where ^ (caret) matches start of line, \s matches space, and A B C and D are numbers (1 or more digits). The use of the parenthesis following the first / provides Perl's regular expression engine the ability to do what is called "backreferencing" (using $1 and $2 after the second /).

Let me know if that code works for you, and if there's anything else you'd like to do.

-verbal </CODE>

Verbal, I tried your method but I still get an error. It takes the file in however, it does nothing with it. how come??

#!/usr/local/bin/perl

                       print "Input file name: ";
                       $_ = <>;
                       chop;
                       open(INFILE, $_);
                       while (<INFILE>)
                       {
                               if (m/total/)
                               {
                                       s/^total\s[0-9]+\s[0-9]+\s([0-9
+]+)\s([0-9]+)$/$1 $2/;
                                       print;
                               }
                       }
                       close INFILE;
[download]

Thanks a lot for yout help.. Paav

Verbal, I tried the code out the way you had asked.It takes the input in however, it doesn't do anything with it. By the way, I am the one, who is trying to read the total from a file, and spit it out to another file. My code reads following:

print "Input file name: ";
$_ = <>;
chop;
open(INFILE, $_);
while (<INFILE>)
{
    if(m/total/)
        {
            s/^total\s[0-9]+\s[0-9]+\s([0-9]+)\s([0-9]+)$/$1 $2/;
            print;
        }
    }
close INFILE
[download]

I think the program is getting the input, however it is just not doing anything with it. Once I enter the name of the file, it just sits there, instead of parsing. How come?? THanks Paav

Verbal, I tried the code out the way you had asked.It takes the input in however, it doesn't do anything with it. By the way, I am the one, who is trying to read the total from a file, and spit it out to another file. My code reads following:

print "Input file name: ";
$_ = <>;
chop;
open(INFILE, $_);
    while (<INFILE>)
      {
         if (m/total/)
            {
                s/^total\s[0-9]+\s[0-9]+\s([0-9]+)\s([0-9]+)$/$1 $2/;
                print;
             }
           }
         close INFILE;
[download]

I think the codes seems OK. THe name of the file that i will be reading the data from is called, "elements". My question is, I am not sure if the file is even being read, or parsed. How would I print out the parsed information?? Thanks Paav

I don't know what you're doing there. It seems you've solved your initial problem, but that code isn't going to work correctly. Here's some code that may do what you want:

#!/usr/local/bin/perl -w
use strict;

while (<>) {
    next if !/^total/;

    my @fields = split /\s+/;
    my($day, $total) = @fields[3,4];

    ## Now graph the values or do whatever you
    ## want with them.
    ...

    ## This will exit the loop after it's seen
    ## the first "total" line. If you don't want
    ## to do this (if, for example, you'll have
    ## several "total" lines, each of which you
    ## want to graph), take out this line.
    last;
}
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To be invoked as such:

    % foo.pl <filename>
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