Re: trying to understand how regex works
Ron Grabowski <[EMAIL PROTECTED]> wrote:
> my $regex = join '|', 'value_garbage1',
> 'value_garbage2',
> 'value_garbage3';
> next if /$regex/;
You might want to say "next if /$regex/o" to prevent Perl from compiling
every time. If you're Perl 5.6, you could even make use of the sexy new qr
{} operator, which returns a reference to a compiled regular expression:
my $regex = join '|', ...
my $re = qr{$regex};
next if /$re/;
Tom Wyant
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RE: trying to understand how regex works
I'd add the check for the garbage before I split, not sure if it would
really add any time to the program running but would, I think, reduce the
amount of checking needed after the split function.
next if(/value_garbage/g); # assuming value_garbage is the exact string.
or you can use:
while {
p = "N";
my @f = split /\s*\|\s*/, $_ unless(m/value_garbage/g);
if (@f != 30) { #^^
print "Field count is ", scalar @f, " should be 30\n";
# error processing ...
}
if ($f[1] =~ / ...
...
This is again assuming that value_garbage is a string...if not, then well,
"if, elsif" away :)
But I would absolutely use the split function
Joe Youngquist
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of
$Bill Luebkert
Sent: Tuesday, August 13, 2002 12:39 AM
To: Dan Jablonsky
Cc: [EMAIL PROTECTED]
Subject: Re: trying to understand how regex works
Dan Jablonsky wrote:
> Hi all,
> I guess it must be a simple problem, but it's a
> mystery to me.
> I got 30 "fields" all separated by pipes in some files
> with many many lines. Some of the fields need to be
> changed, but mostly I have to drop any line that has
> certain values in certain fields.
> So I start by skipping any field that has garbage in
> it:
> open FOUT, ">>/some/path/outputfile.txt";
> open FILE " while{
> p="N";
> next if (/.*?\|value_garbage1\|.*?/ ||
> /.*?\|value_garbage2\|.*?/ ||
> /.*?\|value_garbage3\|.*?/);
> #and then I continue with an if
> if(/(.*?)\|(.*?)\|30 times/){
> $p="Y";
> do something to $1; #change field 1
> do something to $3; #change filed 3
> $fld1=$newfld1;
> $fld2=$2;
> $fld3=$newfld3;
> $fld4=$4;and so on
> }
> print FOUT "$fld1|$fld2|...|$fld30|\n" if ($p="Y");
> #print the whole thing to the new output
> }
>
> Well, it happens that some of the lines are completely
> out of whack and the regex simply stops there - it
> doesn't exit, no errors but goes into an infinite loop
> even though I don't know how exactly is this possible.
> My second if states clearly (or not so clearly) that
> if the line does not have 30 fields it should skip the
> block, it should NOT print anything at the handle and
> should get the next line.
> For whatever reason, the first time it encounters a
> line with less that 30 fields, it just loops without
> end.
> I tried to solve this by replacing the .*? in the
> references by the actual format of each field and
> suddenly it started working but now the regex is a
> hundred times slower and the only thing that speeds it
> up is to go back to the .*? that really goes fast as
> long as the regex "is true". I mean if I have 30
> fields all the time, the regex works OK and it goes
> very fast.
>
> Anybody cares to explain this to me?
No, but I'll offer an alternative.
while {
p = "N";
my @f = split /\s*\|\s*/, $_;
if (@f != 30) {
print "Field count is ", scalar @f, " should be 30\n";
# error processing ...
}
if ($f[1] =~ / ...
...
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Re: trying to understand how regex works
On 13/08/2002 06:26:59 perl-win32-users-admin wrote: >Hi all, >I guess it must be a simple problem, but it's a >mystery to me. [snip question involving regex] > >Anybody cares to explain this to me? Try running your script with perl -re=debug scriptname.pl 2>re_debug Make sure you redirect stderr to a file, as there's plenty of it. -- Csaba Ráduly, Software Engineer Sophos Anti-Virus email: [EMAIL PROTECTED]http://www.sophos.com US Support: +1 888 SOPHOS 9 UK Support: +44 1235 559933 ___ Perl-Win32-Users mailing list [EMAIL PROTECTED] To unsubscribe: http://listserv.ActiveState.com/mailman/mysubs
Re: trying to understand how regex works
> open FOUT, ">>/some/path/outputfile.txt";
> open FILE ">/some/path/outputfile.txt") or
die("Error: $!");
open(FILE " while{
> p="N";
> next if (/.*?\|value_garbage1\|.*?/ ||
> /.*?\|value_garbage2\|.*?/ ||
> /.*?\|value_garbage3\|.*?/);
my $regex = join '|', 'value_garbage1',
'value_garbage2',
'value_garbage3';
next if /$regex/;
> if(/(.*?)\|(.*?)\|30 times/){
> $p="Y";
> do something to $1; #change field 1
> do something to $3; #change filed 3
> $fld1=$newfld1;
> $fld2=$2;
> $fld3=$newfld3;
> $fld4=$4;and so on
> }
> print FOUT "$fld1|$fld2|...|$fld30|\n" if ($p="Y");
If you put the print inside of the if(), you don't need $p. Look into
the join() function:
print FOUT join '|', $fld1, $fld2, $fld3;
print FOUT join '|', @array;
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Re: trying to understand how regex works
Dan Jablonsky wrote:
> Hi all,
> I guess it must be a simple problem, but it's a
> mystery to me.
> I got 30 "fields" all separated by pipes in some files
> with many many lines. Some of the fields need to be
> changed, but mostly I have to drop any line that has
> certain values in certain fields.
> So I start by skipping any field that has garbage in
> it:
> open FOUT, ">>/some/path/outputfile.txt";
> open FILE " while{
> p="N";
> next if (/.*?\|value_garbage1\|.*?/ ||
> /.*?\|value_garbage2\|.*?/ ||
> /.*?\|value_garbage3\|.*?/);
> #and then I continue with an if
> if(/(.*?)\|(.*?)\|30 times/){
> $p="Y";
> do something to $1; #change field 1
> do something to $3; #change filed 3
> $fld1=$newfld1;
> $fld2=$2;
> $fld3=$newfld3;
> $fld4=$4;and so on
> }
> print FOUT "$fld1|$fld2|...|$fld30|\n" if ($p="Y");
> #print the whole thing to the new output
> }
>
> Well, it happens that some of the lines are completely
> out of whack and the regex simply stops there - it
> doesn't exit, no errors but goes into an infinite loop
> even though I don't know how exactly is this possible.
> My second if states clearly (or not so clearly) that
> if the line does not have 30 fields it should skip the
> block, it should NOT print anything at the handle and
> should get the next line.
> For whatever reason, the first time it encounters a
> line with less that 30 fields, it just loops without
> end.
> I tried to solve this by replacing the .*? in the
> references by the actual format of each field and
> suddenly it started working but now the regex is a
> hundred times slower and the only thing that speeds it
> up is to go back to the .*? that really goes fast as
> long as the regex "is true". I mean if I have 30
> fields all the time, the regex works OK and it goes
> very fast.
>
> Anybody cares to explain this to me?
No, but I'll offer an alternative.
while {
p = "N";
my @f = split /\s*\|\s*/, $_;
if (@f != 30) {
print "Field count is ", scalar @f, " should be 30\n";
# error processing ...
}
if ($f[1] =~ / ...
...
--
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-/-' /___/_<_http://www.todbe.com/
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