use warnings; use strict; my $prev; while () { chomp; if (/\+/) { print length($prev), "\n"; } $prev = $_; } __DATA__ @HWI-ST591:68:D0DBPABXX:5:1101:1197:2084 1:N:0: GGTAGTTCGACCGTGGAT + B@@FFEFFHDHHFHIJJE @HWI-ST591:68:D0DBPABXX:5:1101:1086:2085 1:N:0: GCTGGAACTTGGCAAAGAAGAGAG + @@@FFEFFGHHHH@@FEHBEHJGG