Re: Regex to match "bad" characters in a parameter
"Chris Charley" writes:
> You could do that in 1 line - See the following small program.
> (The line using a 'grep' solution is commented out. It would work as well).
>
>
> #!/usr/bin/perl
> use strict;
> use warnings;
>
> while (my $id = ) {
>chomp $id;
>#if (grep /itemid=.*?[^\w-]/, split /&/, $id) {
>if ($id =~ /itemid/ && $id !~ /itemid=[\w-]+(?:&|$)/) {
>print "Bad id: <$id>\n";
>}
> }
>
> __DATA__
> itemid=AT18C&i_AT18C=1&t=main.htm&storeid=1&cols=1&c=detail.htm&ordering=asc
> c=detail.htm&itemid=AT18C
> itemid=AT18/C
> t=main.htm&storeid=1&cols=1&c=detail.htm&ordering=asc
This might be a string with a bad item id because there is none: Are you
going to process the string, assuming that it is a good item id?
How do you determine the beginning of the relevant sequence --- and thus
whether the string contains a good item id or not --- when the string
might not contain 'itemid' to designate the beginning?
I think you might need to work with cleaner definitions, and/or attempt
to find the good item ids instead of the bad ones.
> itemid=?AT18C
>
>
> When this is run, it prints out:
>
> Bad id:
> Bad id:
>
> Chris
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Re: Regex to match "bad" characters in a parameter
On Jan 26, 2016, at 11:22 AM, Chris Charley wrote: > > You could do that in 1 line - See the following small program. Thanks, Chris. That'll do the trick. And the grep alternative is interesting, too. I hadn't thought of that. Regards, Frank -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Regex to match "bad" characters in a parameter
"SSC_perl" wrote in message
news:ef7499af-b4a5-4b07-8c69-3192ef782...@surfshopcart.com...
On Jan 25, 2016, at 4:59 PM, Shawn H Corey wrote:
Use the negative match operator !~
if( $QUERY_STRING !~ m{ itemid = [-0-9A-Za-z_]+? (?: \& | \z ) }msx ){
print "bad: $QUERY_STRING\n";
}
Thanks for that, Shawn. It works perfectly except for one criteria that I
inadvertently forgot to >include. It's possible that the string will _not_
contain the itemid parameter at all. When that's >missing, the regex
matches and it shouldn't. I guess that's why I was trying to stay with the
>positive match operator.
I tried inverting your regex:
if ( $QUERY_STRING =~ m/ itemid= .*? [^-0-9A-Za-z_]+? .*? (?: \& | \z )
/sx ) {
> say "bad: $QUERY_STRING";
}
but that doesn't work either. It catches even good item numbers.
In the meantime, I got it to work by grabbing the itemid and working with
that separately:
my $item_id = $1 if ($QUERY_STRING =~ m/ itemid=([^&]*) /x);
if ( $item_id =~ m/ [^a-zA-Z0-9_-] /x ) { ...
however, I'd like to do that with a single line, if possible, so I don't
have to create a new variable >just for that.
Thanks,
Frank=
###
###
Hello Frank,
You could do that in 1 line - See the following small program.
(The line using a 'grep' solution is commented out. It would work as well).
#!/usr/bin/perl
use strict;
use warnings;
while (my $id = ) {
chomp $id;
#if (grep /itemid=.*?[^\w-]/, split /&/, $id) {
if ($id =~ /itemid/ && $id !~ /itemid=[\w-]+(?:&|$)/) {
print "Bad id: <$id>\n";
}
}
__DATA__
itemid=AT18C&i_AT18C=1&t=main.htm&storeid=1&cols=1&c=detail.htm&ordering=asc
c=detail.htm&itemid=AT18C
itemid=AT18/C
t=main.htm&storeid=1&cols=1&c=detail.htm&ordering=asc
itemid=?AT18C
When this is run, it prints out:
Bad id:
Bad id:
Chris
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Re: Regex to match "bad" characters in a parameter
On Jan 25, 2016, at 4:59 PM, Shawn H Corey wrote:
>
> Use the negative match operator !~
>
> if( $QUERY_STRING !~ m{ itemid = [-0-9A-Za-z_]+? (?: \& | \z ) }msx ){
>print "bad: $QUERY_STRING\n";
> }
Thanks for that, Shawn. It works perfectly except for one criteria
that I inadvertently forgot to include. It's possible that the string will
_not_ contain the itemid parameter at all. When that's missing, the regex
matches and it shouldn't. I guess that's why I was trying to stay with the
positive match operator.
I tried inverting your regex:
if ( $QUERY_STRING =~ m/ itemid= .*? [^-0-9A-Za-z_]+? .*? (?: \& | \z ) /sx ) {
say "bad: $QUERY_STRING";
}
but that doesn't work either. It catches even good item numbers.
In the meantime, I got it to work by grabbing the itemid and working
with that separately:
my $item_id = $1 if ($QUERY_STRING =~ m/ itemid=([^&]*) /x);
if ( $item_id =~ m/ [^a-zA-Z0-9_-] /x ) { ...
however, I'd like to do that with a single line, if possible, so I don't have
to create a new variable just for that.
Thanks,
Frank
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Re: Regex to match "bad" characters in a parameter
On Mon, 25 Jan 2016 16:16:40 -0800
SSC_perl wrote:
> I'm trying to find a way to trap bad item numbers. I want to
> parse the parameter "itemid=" and then everything up to either an "&"
> or end-of-string. A good item number will contain only ASCII
> letters, numbers, dashes, and underscores and may terminate with a
> "&" or it may not (see samples below). The following string should
> test negative in the regex below:
>
> my $QUERY_STRING = 'itemid=AT18C&i_AT18C=1';
>
> but a string containing "itemid=AT18/C" should test positive, since
> it has a slash.
>
> I can catch a single bad character and get it to work, e.g.
>
> if ( $QUERY_STRING =~ m| itemid= .*? [/]+? .*? &? |x ) {
>
> but I'd like to do something like this instead to catch others:
>
> if ( $QUERY_STRING =~ m| itemid= (?: .*? [^a-zA-Z0_-]+ .*? ) &? |x )
> { ...
>
> Unfortunately, I can't get it to work. I've read perlretut,
> but can't see the answer. What am I doing wrong?
>
> Thanks,
> Frank
>
> Here are a couple of test strings:
>
> 'itemid=AT18C&i_AT18C=1&t=main.htm&storeid=1&cols=1&c=detail.htm&ordering=asc'
>
> 'c=detail.htm&itemid=AT18C'
>
>
>
>
Use the negative match operator !~
if( $QUERY_STRING !~ m{ itemid = [-0-9A-Za-z_]+? (?: \& | \z ) }msx ){
print "bad: $QUERY_STRING\n";
}
--
Don't stop where the ink does.
Shawn
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Regex to match "bad" characters in a parameter
I'm trying to find a way to trap bad item numbers. I want to parse the
parameter "itemid=" and then everything up to either an "&" or end-of-string.
A good item number will contain only ASCII letters, numbers, dashes, and
underscores and may terminate with a "&" or it may not (see samples below).
The following string should test negative in the regex below:
my $QUERY_STRING = 'itemid=AT18C&i_AT18C=1';
but a string containing "itemid=AT18/C" should test positive, since it has a
slash.
I can catch a single bad character and get it to work, e.g.
if ( $QUERY_STRING =~ m| itemid= .*? [/]+? .*? &? |x ) {
but I'd like to do something like this instead to catch others:
if ( $QUERY_STRING =~ m| itemid= (?: .*? [^a-zA-Z0_-]+ .*? ) &? |x ) { ...
Unfortunately, I can't get it to work. I've read perlretut, but can't
see the answer. What am I doing wrong?
Thanks,
Frank
Here are a couple of test strings:
'itemid=AT18C&i_AT18C=1&t=main.htm&storeid=1&cols=1&c=detail.htm&ordering=asc'
'c=detail.htm&itemid=AT18C'
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