Re: Simple regex question. Grouping with a negative lookahead assertion.

Select or download this

$ perl -Mstrict -Mwarnings -E '
    my $dna = q{atctcggataatgggataaaaatataggctataaatggcgccccggctaatttt
+t};
...
    }
'
ggataaaaatataggctataaatggcgccccggctaattttt

Select or download this

$ perl -Mstrict -Mwarnings -E '
    my $dna = q{atctcggataatgggataaaaatataggctataaatggcgccccggctaatttt
+t};
...
    }
'
ggataaaaatataggctataaatggcgccccggc

Select or download this

$ perl -Mstrict -Mwarnings -E '
    my $dna = q{atctcggataatgggataaaaatataggctataaatggcgccccggctaatttt
+t};
...
    }
'
gga

Select or download this

$ perl -Mstrict -Mwarnings -E '
    my $dna = q{atctcggataatgggataaaaatataggctataaatggcgccccggctaatttt
+t};
...
    }
'
gga

Select or download this

/atg (.+?) (?>taa|tag|tga)/msx

Select Code to Download