number format to float php

$num = '1,200,998.255';

########## FOR FLOAT VALUES ###########################

echo filter_var($num, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_FRACTION);

#output  : 1200998.255

########## FOR INTEGER VALUES ###########################

echo filter_var($num, FILTER_SANITIZE_NUMBER_INT);

#output  : 1200998