<?php
define(
'FLOAT',
';\s*?q=
(1|0 # 1 or 0
(\. # Literal dot
([0-9]{1,2}[1-9]| # One or Two Zeroes followed by 1...9 -OR-
[0-9][1-9][0-9]?| # Zero followed by 1...9, followed by an optional 0...9 -OR-
[1-9] # 1...9 followed by:
([0-9]{0,2}| # None and up to Two 0...9 -OR-
[0-9][1-9]| # 0...9 and then followed by 1...9 -OR-
[1-9]{1,2} # 1...9 once and up to three
)
)(?![0-9])
)? # All this is optional, and refers to float range
(?!\.)
)'
);
preg_match( sprintf( '@(?<params>%s)@x', FLOAT ), ';q=0.3444', $matches );
var_dump( $matches );