in reply to Re^2: Definition of numerically equal and rationale for 'you' == 'me'
in thread Definition of numerically equal and rationale for 'you' == 'me'

As already noted, it's not actually done "character by character".

No, it was (correctly) said that skipping the leading non-number part isn't done at all.

If it were done that way 'nanosecond' == 'nanosecond' and 'informal' == 'formal' would both be true.

They are both true even though it's not done that way, so that's a useless statement.

  • Comment on Re^3: Definition of numerically equal and rationale for 'you' == 'me'

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Re^4: Definition of numerically equal and rationale for 'you' == 'me'
by syphilis (Archbishop) on Mar 02, 2012 at 10:53 UTC
    They are both true

    Where are they both true ?
    Did you even bother testing it ?

    Quite frankly, I regard it as an insult that you so quickly assume I'm just another moron.

    On Windows, perl-5.14.0: 
    C:\>perl -e "print \"true\" if 'nanosecond'== 'nanosecond'"

C:\>perl -e "print \"true\" if 'nanosecond'!= 'nanosecond'"
true
C:\>perl -e "print \"true\" if 'informal'== 'formal'"

C:\>perl -e "print \"true\" if 'informal'!= 'formal'"
true
C:\>

    [download]
    Should be the same most places.

    Rob
[reply]
[d/l]

      I get exactly the opposite results under 5.8.8 and 5.8.9, hpux, msys, and windows. One such example: 

      $ perl -e "print \"true\" if 'informal'== 'formal'"
true

      [download]

      Update: Under strawberry 5.14.2 MSWin32-x86-multi-thread, the results are different: 

      $ /c/perl/strawberry/perl/bin/perl -e "print \"true\" if 'informal'!= 
+'formal'"
true

$ /c/perl/strawberry/perl/bin/perl -e "print \"true\" if 'informal'== 
+'formal'"

      [download]

      Update: Ahhhh! Very sneaky :-).

      <Reveal this spoiler or all in this thread>

      --MidLifeXis

[reply]
[d/l]
[select]
        I get exactly the opposite results under 5.8.8 and 5.8.9, hpux, msys, and windows

        The compiler that was used to build perl affects the behaviour.
        On Windows, ActivePerl (built using Microsoft Compilers) apparently doesn't display the behaviour, but MinGW-built perls do.
        And I think there's a fairly recent perl that throws another spanner in the works by asserting (incorrectly) that nan==nan is true.

        I'm surprised that hpux and msys make a liar out of me with 5.8.9. On my linux box (an old Mandrake-9.1), behaviour is as I asserted with 5.8.9 onwards.

        Cheers,
        Rob
[reply]

      Yes, even though I knew the result, I did test. I even used 5.14.0 on Windows like you. (ActivePerl build 1400, to be specific.) 

      >perl -e "print \"true\" if 'nanosecond'== 'nanosecond'"
true
>perl -e "print \"true\" if 'nanosecond'!= 'nanosecond'"

>perl -e "print \"true\" if 'informal'== 'formal'"
true
>perl -e "print \"true\" if 'informal'!= 'formal'"

>

      [download]

      'nanosecond', 'informal' and 'formal' are all numerically equal to zero, so your build is very buggy.

[reply]
[d/l]
[select]
        so your build is very buggy

        Oh, of course ... *my* pathetic dumbarse build is buggy ... how could I *not* have realised this !!

        Now, excuse me while I go puke somewhere ....

        Rob
[reply]

        I'm coming in a little late, but this is what I got on Mac Lion, perl-5.14.2:

        perl -e "print \"true\" if 'nanosecond'== 'nanosecond'"

perl -e "print \"true\" if 'nanosecond'!= 'nanosecond'"
true

perl -e "print \"true\" if 'informal'== 'formal'"

perl -e "print \"true\" if 'informal'!= 'formal'"
true

        [download]

        strange

        Update: Oh I see ... 'nan'...'inf'

[reply]
[d/l]

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