CODEWITHSUNDEEP
perlmatching
snkatore
snkatore

Reputation: 47

How do match the two strings which contains parentheses in perl

How do match the two strings which contains brackets.

the perl code is here.

#!/usr/bin/perl -w

$a = "cat(S1)rat";
$b = "cat(S1)r";

if ( $a =~ $b ) {
    printf("matching\n");
}

I am not getting the desired output.

please help

snk

Upvotes: 0

Views: 1652

Answers (3)

jwd
jwd

Reputation: 11124

There are several answers here, but not a lot address your fundamental misunderstanding.

Here is a simplified version of your problem:

my $str = "tex(t)";
my $pattern = "tex(t)";

if ($str =~ $pattern) {
  print "match\n";
} else {
  print "NO MATCH\n";
}

This prints out NO MATCH.

The reason for this is the behavior of the =~ operator. The thing on the left of that operator is treated as a string, and the thing on the right is treated as a pattern (a regular expression).

Parentheses have special meaning in patterns, but not in strings.

For the specific example above, you could fix it with:

my $str = "tex(t)";
my $pattern = "tex\\(t\\)";

More generally, if you want to escape "special characters" in $pattern (such as *, ., etc.), you can use the \Q...\E syntax others have mentioned.

Does it make sense?

Typically, you do not see a pattern represented as a string (as with "tex(t)"). The more common way to write this would be:

if ($str =~ /tex(t)/)

Which could be fixed by writing:

if ($str =~ /tex\(t\)/)

Note that in this case, since you are using a regex object (the /.../ syntax), you do not need to double-escape the backslashes, as we did for the quoted string.

Upvotes: 3

Toto
Toto

Reputation: 91478

You have to escape the parenthesis:

if ( $a =~ /\Q$b/ ) {
    print "matching\n";
}

And please, avoid using variable names $a and $b they are reserved for sorting.
Also, there're no needs to use printf here.

Upvotes: 1

Praveen
Praveen

Reputation: 902

Try this code:

my $p = "cat(S1)rat";
my $q = "cat(S1)r";

if ( index( $p, $q ) == -1 ) {
    print "Does not match";
} else {
    print "Match";
}

Upvotes: 1

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