File Manipulation/Parsing in Perl.

[Archon]

Okay, I'm trying to pull a few values out of a flat txt file, and set them to variables.

Example:

blah blah blah blah weight 2kg blah blah blah

What would be the method/syntax to search the file and set $weight = (in this case) 2 when I don't know what the value will be, or where in the file it will be?

Any help would be greatly appreciated,
Thanks

Archon

 

[Haunter]

What is the exact format of the test to be matched? It makes a difference in finding a stable Regular expression. Can you give us some indication of what the rest of the file represents or how the data will be represented. On what you have given me I would do this
#!/usr/bin/perl
$fullpathtothefile='c:/test/test.txt';

open(DFILE,&quot;< $fullpathtothefile\0&quot || die (print qq(&quot;Failed to open DFILE, $!&quot);
while (read(DFILE, $newtext,1)){
$data1 .=$newtext;
}
close (DFILE);

$data1 =~ /(\bweight\b[\s]?)([0-9]+)/;
$weight=$2;

print &quot;Our new variable \$weight = $weight&quot; ;

I will break down the Regular Expression for you to help you use it over and over
(\bweight\b[\s]?)<--this matches the word preceiding the number you want to set it two in this case weight. YOu will have to be careful because this is a gready expression and will match more than once. So if you have more than one weight in the file it will match it. This match is stored in $1.

([0-9]+)<---will match any number after the previous match and stores this value in the variable $1.

 

[Haunter]

err replace this $data1 =~ /(\bweight\b<\s>?)([0-9]+)/;

with $data1 =~ /(\bweight\b[\s]?)([0-9]+)/;

hope this helps

 

[Haunter]

Well there is an error in the board postin apparently.

The <> that surround the \s should be brackets. It just will not let me post it that way.

It should look like this with no spaces:
[ \s ]

 

[Archon]

I tried the code, even toyed with it.. but I get no value. As if it's not finding the match, but I've been running it on a test file that I know has the match. Would it be easier if I read it into a string first?

An exact example of the text I'm searching through would be:

--- Garbage Line ---
and has weight 2kg with blah blah
--- Garbage Line ---

What I need to do is be able to search through this and pull 2 into a variable (naturally it won't be 2 every time.)
I need to do this with several variables, but they're all set up the same way.

Thanks,
Archon

 

[LightElf]

open (FILE, &quot;<$file&quot;
while (<FILE>){
$weight = $1 if ($_ =~ /\bweight\s+(\d+)\s+/);
}
close FILE;

 

[three]

Please advise how I would print results to the screen?
I can only get it to print the whole file contents instead of
printing out the variable and number 2.

[tt]

$db = 'tex.doc';
open(FILE, &quot;<$db&quot or die &quot;File does not open: $!&quot;;
#@data = (<DATA>);
#close (DATA);
#open(DATA, &quot;>$db&quot or die &quot;File not open: $!&quot;;

while (<FILE>)
{
$weight = $1 if ($_ =~ /\bweight\s+(\d+)\s+/);
print;
}
close FILE;[/tt]

I used file (tex.doc) as mentioned earlier:
[tt]
test test
nd has weight 2kg with blah blah
test[/tt]

 

[Haunter]

$weight = $1 if ($_ =~ /\bweight\s+(\d+)\s+/);
print $weight;#<-make this change

PERL has to be told what to print or it will pull from the $_ variable for its source to print.

If this a CGI program you will neet to print the HTTP headers.

example
print &quot;Content type: text/html&quot;;
print &quot;This is the persons weight: $weight&quot;;

If you just are using the standard commandline output.

print $weight;

will do.

 

[three]

Still no luck I tried:[tt]
print $weight;
print $_;
print FILE;[/tt]

and none of the above printed out weight 2.

MOst of the print outs were of the whole file such as:
--- Garbage Line ---
and has weight 2kg with blah blah
--- Garbage Line ---

Any other suggestions??

 

[yauncin]

Theres a problem with the regex:
instead of
($_ =~ /\bweight\s+(\d+)\s+/)
try
($_ =~ /\bweight\s+(\d+)/)

 

[LightElf]

print &quot;weight: $weight&quot;;

 

[three]

I got the output I wanted and was wondering it this is the best way to do it??

[tt]
$db = 'aaa.txt';
open(FILE, &quot;$db&quot or die &quot;File does not open: $!&quot;;


while(<FILE>)
{
if ($weight = (/\b(weight)(\s+)(\d+)/))
{
print $1 . $2 . $3;
}
}
close FILE;[/tt]

 

[zephan]

If you are sure that the number (eg 2) is followed by 'kg' (eg 2kg), i think you may use the regex :

/\bweight\s+(\d+)kg/

instead of :

/\bweight\s+(\d+)\s+/

cause there are no spaces after the number, isn't ? If both cases are possible, use :

/\bweight\s+(\d+)\s*kg/


What do you think ?