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Using variable $& for getting result

FiMko
New User

Jan 11, 2010, 8:47 AM

Post #1 of 3 (1761 views)

Using variable $& for getting result	Can't Post

Hi all!

I need your help in very simple problem.

I have a file content like:

Code

string1 
  string2 
string3

And I have a perl script parsing this file:

Code

if(scalar(@ARGV) == 0) { 
    print "None of file paths is specified!"; 
    exit; 
} 
# for all the specified files 
for ($i = 0; $i < @ARGV; $i++) { 
    $file_path = $ARGV[$i]; 
    open(IN, $file_path) || die; # read next file 
    while ($line = <IN>) { 
        $line =~ m/^[^\s].+$/; 
        print $& . "\n"; 
     } 
     close (IN); 
}

So, I expect the following out:

Code

string1 
string3

But have the following:

Code

string1 
string1 
string3

In the second pass the regular expression does not match a text, but variable $& keeps its value from the previous pass ("string1"). This is printed out.

What should I do in such cases? I can't clear variable $& as it is readonly. Could you please give me a hint, I can't find an info in any guide. Thanks in advance!

(This post was edited by FiMko on Jan 11, 2010, 8:50 AM)

toolic
User

Jan 11, 2010, 10:02 AM

Post #2 of 3 (1754 views)

Re: [FiMko] Using variable $& for getting result [In reply to]	Can't Post

Print the line only if no leading space is found:

Code

while ($line = <IN>) {  
        print $line unless $line =~ m/^\s/;  
}

FiMko
New User

Jan 11, 2010, 10:57 AM

Post #3 of 3 (1750 views)

Re: [toolic] Using variable $& for getting result [In reply to]	Can't Post

toolic, thanks for help!

Here is one more way to do what I wanted:

Code

if(scalar(@ARGV) == 0) { 
    print "None of file paths is specified!"; 
    exit; 
} 
# for all the specified files 
for ($i = 0; $i < @ARGV; $i++) { 
    $file_path = $ARGV[$i]; 
    open(IN, $file_path) || die; # read next file 
    while ($line = <IN>) { 
         if ($line =~ m/^[^\s].+$/) { // operator =~ returns 1 if a match found! 
              print $& . "\n"; 
         } 
     } 
     close (IN); 
}

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