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perl regex help needed

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# 1  
Old 09-16-2012
perl regex help needed
Hi,

I want to validate strings in perl, the string may contains characters from a-zA-Z0-9 and symbols +-_.:/\

To validate such a string I computed a regex

Code:
if ($string =~ m/^[a-zA-Z0-9+-_.:\/\\]/) {
   print "valid";
} else {
   print "invalid";
}

but this regex also validates strings that contain other characters like @%^&*?.

I want to disallow strings which contain all other characters from above valid set.

plz help me

thanks,
zing_foru
Last edited by Scott; 09-16-2012 at 08:47 AM.. Reason: Code tags
# 2  
Old 09-16-2012
Code:
if ($string =~ m{\A[-+.:/\\a-zA-Z0-9_]+\z}) {
print "valid";
} else {
print "invalid";
}

and if you have Perl 5.14+, you could replace the first line with:
Code:
if ($string =~ m{\A[-+.:/\\\w]+\z}a) {

Last edited by elixir_sinari; 09-16-2012 at 12:24 PM..
# 3  
Old 09-16-2012
If an empty string is allowed, you could also negate the bracketed expression, rendering anchors unnecessary.

Regards,
Alister
# 4  
Old 09-16-2012
thanks elixir_sinari, but this regex even not validating correct strings
Code:
e.g. "e:\test1\test2"
      "/usr/bin/test"
      "/var/log-test"
      "/usr/test bin/goak"

invalid strings e.g.

Code:
"e:\test\test?newdata"  #contains ? invalid symbol
"goak&<>"  #contains & <> invalid symbol

Last edited by Scott; 09-16-2012 at 08:48 AM.. Reason: Please use code tags
# 5  
Old 09-16-2012
Try this Reg Exp

Code:
if($string =~ m/^[\w\s+-.:\/\\]*$/)
{
print "Valid";
}else {
print "Invalid"
}

# 6  
Old 09-16-2012
MySQL
thanks msabhi.. worked Smilie
# 7  
Old 09-16-2012
Quote:
Originally Posted by zing_foru
thanks msabhi.. worked Smilie
No, it did not. You just did not notice the error. A comma is still allowed even though it's not on your list of allowed characters.

The portions highlighted in red represent ranges of characters, not the three characters which appear literally in the regular expression.

Quote:
Originally Posted by zing_foru
I want to validate strings in perl, the string may contains characters from a-zA-Z0-9 and symbols +-_.:/\
Code:
/^[a-zA-Z0-9+-_.:\/\\]/

but this regex also validates strings that contain other characters like @%^&*?

Quote:
Originally Posted by msabhi
Try this Reg Exp
Code:
/^[\w\s+-.:\/\\]*$/

Neither of those is correct. msabhi's example is simply less wrong. zing_foru's unintended range expression spans the entirety of the following list. msabhi's attempt spans the highlighted section.

From POSIX - Locale - collation sequence
Code:
<plus-sign>
<comma>
<hyphen>
<period>
<slash>
<zero>
<one>
<two>
<three>
<four>
<five>
<six>
<seven>
<eight>
<nine>
<colon>
<semicolon>
<less-than-sign>
<equals-sign>
<greater-than-sign>
<question-mark>
<commercial-at>
<A>
<B>
<C>
<D>
<E>
<F>
<G>
<H>
<I>
<J>
<K>
<L>
<M>
<N>
<O>
<P>
<Q>
<R>
<S>
<T>
<U>
<V>
<W>
<X>
<Y>
<Z>
<left-square-bracket>
<backslash>
<right-square-bracket>
<circumflex>
<underscore>

To fix your errors, refer to the perlre man page @ perldoc.perl.org
Quote:
Within a list, the "-" character specifies a range, so that a-z represents all characters between "a" and "z", inclusive. If you want either "-" or "]" itself to be a member of a class, put it at the start of the list (possibly after a "^"), or escape it with a backslash. "-" is also taken literally when it is at the end of the list, just before the closing "]".
Regards,
Alister
This User Gave Thanks to alister For This Post:
msabhi
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