On Mar 17, 7:40 am, [EMAIL PROTECTED] (Irfan Sayed) wrote:
> Hi All,
>
> Can somebody please let me know the meaning of this line.
>
> while (<$in>)
>
> {
>
> if(/,/) {print "before match: $`\t and after match: $'\n\n";}; $x=$';
> $y=$`; &mysubroutine($x,$y);
>
> }
>
> I know it is a while loop for the file handle ($in) and it will be
> executed till the end of file but not getting the meaning of if loop.
>
> What this if loop actually does. Please help
Does it help to see it this way?
while (<$in>) {
if (/,/) { # Check each line of $in for a match of ,
(the comma)
print "before match: $`\t and after match: $'\n\n"; # Print
strings captured before and after the comma
$x = $'; # Assign $x whatever is in $'
$y = $`; # Assign $y whatever is in $`
&mysubroutine($x, $y); # Call the subroutine "mysubroutine"
with $x and $y as parameters
}
}
The variables $` $& and $' are special. They match (repectively) $` -
the stuff before your match, $& - what you match, and $' - the stuff
left after your match. Many people avoid them like the plague since
they slow down regular expression matching. (Check perldoc perlvar.)
As to what <mysubroutine> actually *does*, there's no way to know
without seeing the code for that subroutine.
Hope this helps, T
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