in reply to Reguar expression

That's not very complicated: 
#!/usr/bin/perl

$_ = "This is first sentence.";
print "1st: match\n" if (/^This/ and /\.$/ and !/first/);

$_ = "This is second sentence.";
print "2nd: match\n" if (/^This/ and /\.$/ and !/first/);

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Re^2: Reguar expression
by citromatik (Curate) on Jun 22, 2009 at 10:45 UTC
    That's not very complicated:

    Well, maybe, but you are not asking the OP. That is: "I need a regular expression to match the following pattern.". You are using 2. (and perliff above uses 3!).

    Update: Solving the problem with 2+ regexps is more or less trivial, but using just 1 is far more interesting. Here is a solution using look-ahead assertions (see perlre):

    my $re = qr{ ^           # match at the beginning.
             (?!         # Look-ahead assertion: Fail if the next matc
+hes
               .* first  # match "first" everywhere except at the begi
+nning of the string
             )           # end of look-ahead assertion
             This .* \.  # Match "This" (at the beginning), followed b
+y anything and a dot
             $           # Match the end of a string.
         }x;             # Allow these comments

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    citromatik

[reply]
[d/l]
Re^2: Reguar expression
by perliff (Monk) on Jun 22, 2009 at 10:45 UTC
    Nifty work chomzee, I like it, but considering mr. selva has not cared to provide any details into his own problems... and considering unknown issues with his unknown data... I would feel a wee bit safer with this... 
    $_ = "This is first sentence.";
print "1st: match\n" if (/^This/i and /\.$/ and !/\bfirst\b/);

$_ = "This is second sentence.";
print "2nd: match\n" if (/^This/i and /\.$/ and !/\bfirst\b/);

    [download]

    perliff

    ----------------------

    -with perl on my side

    "If you look at the code too long, the code also looks back at you"

[reply]
[d/l]

      That's true, it certainly depends on data and some details that OP didn't give (so your hints are reasonable and useful).

      And it's still three regular expressions not one, but who cares -- the code does the job well. :)

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