the input file isn't in that format. i will have the values in 2 variables called $a and $b after i have parsed the line and i know $b will be higher than a for every row.
You might not want to use $a and $b, because those are built-in globals used by certain functions (eg sort).
Assuming you're looping over each line:
my @pairs;
while (<$filehandle>) { # or whatever loop construct
# parse line and set $foo and $bar here
# for example:
chomp;
my ($foo, $bar) = /(\d+)/g;
# add to array
push @pairs, [ $foo, $bar ];
}
# sort array
# NB: these are the special $a and $b, not yours
@pairs = sort { $$a[0] <=> $$b[0] } @pairs;