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Re: unpack and byteorder - tests fail on certain platforms

by davidrw (Prior)
on Jan 09, 2008 at 15:01 UTC ( #661370=note: print w/ replies, xml ) Need Help??


in reply to unpack and byteorder - tests fail on certain platforms

From pack:

The integer formats s, S , i , I , l , L , j , and J are inherently non-portable between processors and operating systems because they obey the native byteorder and endianness.
...
If you want portable packed integers you can either use the formats n , N , v , and V , or you can use the > and < modifiers. These modifiers are only available as of perl 5.9.2. See also perlport.


Comment on Re: unpack and byteorder - tests fail on certain platforms
Re^2: unpack and byteorder - tests fail on certain platforms
by halley (Prior) on Jan 11, 2008 at 17:47 UTC
    Agreed; a unit test of pack() and unpack() should not be concerned with the actual bytes of platform-dependent packings unless there is an independent, bug-free way of doing the packs and unpacks on that platform. The following would be good tests for the above formats:
    $x = pack($format, $original); ok($original == unpack($format, $x), 'reversible unpack'); $x = external_platform_pack($format, $original); ok($original == unpack($format, $x), 'unpack from platform-specific source'); $x = pack($format, $original); ok($original == external_platform_unpack($format, $x), 'pack to platform-specific source');
    Only the first one is devoid of platform-dependence. Of course, a diverse pool of $original value samples should be run.

    --
    [ e d @ h a l l e y . c c ]

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