use strict;
my $str = '{"city":{"id":1217734,"name":"Boysun","findname":"BOYSUN","country":"UZ","coord":{"lon":67.198608,"lat":38.206108},"zoom":8,"langs":[{"link":"http:\\/\\/en.wikipedia.org\\/wiki\\/Boysun"},{"ru":"Бойсун"}]},"time":1394871628,"main":{"temp":274.74,"temp_min":274.74,"temp_max":274.74,"pressure":823.92,"sea_level":1035.91,"grnd_level":823.92,"humidity":98},"wind":{"speed":0.6,"deg":97.004},"clouds":{"all":92},"weather":[{"id":804,"main":"Clouds","description":"overcast clouds","icon":"04d"}],"rain":{"3h":0.1},"snow":{"3h":0.85}}';
my $regex = qr/(?<="3h":|"3h":)((d+)|\d+\.\d+)(?=)/p;
if ( $str =~ /$regex/g ) {
print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n";
# print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n";
# print "Capture Group 2 is $2 ... and so on\n";
}
# ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p'
# Named capture groups can be called via $+{name}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html