Here is one way of doing it:

    #!/usr/bin/perl -wl


    my $hex =  '0x428C0000';
       $hex =~ s/0x//i; # Strip the hex 0x if present


    print unpack "f", reverse pack "H*", $hex ;
    print unpack "f",         pack "H*", $hex ;



    __END__
    Prints on an a little endian platform:

    70
    5.03150226600469e-041
[download]

In this case the first of these looks like the right value.

It is rare that you will encounter a platform where one of these doesn't work. If you do then I have some Perl code for packing and unpacking IEEE 754 floats and doubles independently of the architecture.

--
John.