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Re: Removing Trailing Whitespace: Multiple ways.

by perlmonkey (Hermit)
on May 12, 2001 at 02:53 UTC ( #79862=note: print w/replies, xml ) Need Help??


in reply to Removing Trailing Whitespace: Multiple ways.

If it is speed you are after, you can always put on your C hat:
use Benchmark; use Inline C; timethese (1000000, { 'regex' => q{ my $foo = "test "; $foo =~ s/\s+$//; }, 'inline' => q{ my $foo = "test "; rmsp($foo); } }); __END__ __C__ void rmsp(char * str) { int i = strlen(str) - 1; while( i >= 0 && str[i] == ' ' ) { str[i--] = '\0'; } }


Results:
Benchmark: timing 1000000 iterations of inline, regex... inline: 4 wallclock secs ( 4.39 usr + 0.03 sys = 4.42 CPU) regex: 8 wallclock secs ( 6.84 usr + 0.03 sys = 6.87 CPU)

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Re: Re: Removing Trailing Whitespace: Multiple ways.
by no_slogan (Deacon) on May 12, 2001 at 03:15 UTC
    That would be really cool, but rmsp() leaves the string null-padded instead of removing the extra blanks.
      Yah, so I was lazy and I cheated a bit. $foo will look good when you print it though. What can I say, there are reasons I am a perl programmer.

      But to be all official like and actually update the scalar value to be a proper string of length 4 you can use this code for rmsp:
      void rmsp(SV * sv) { char * end; int length; if( !SvPOK(sv) ) return; end = SvEND(sv); length = SvCUR(sv); end--; /* skip \0 */ while( *end == ' ' && length >=0 ) { end--; length--; } if( length >= 0 ) SvCUR_set(sv, length); }
      And the new results I got are:
      Benchmark: timing 1000000 iterations of inline, regex... inline: 6 wallclock secs ( 4.19 usr + 0.01 sys = 4.20 CPU) regex: 9 wallclock secs ( 7.71 usr + 0.02 sys = 7.73 CPU)

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[Corion]: marto: How's things? I hope the kids are fine and you too!
[Corion]: Oh yay. I wonder why a very simple change in a program doesn't elicit a diff, and now I see that my diff program seems to have a bug ;)
[1nickt]: marto thanks for asking, so far so good. A pretty modern stack and decent procedures, although rather too much home-built stuff (e.g. a logging role that should tries to duplicate Log::Any).
[Corion]: No. It's just that I'm comparing the same output file twice, instead of comparing the output files of the two runs %-)
[Corion]: Lo and behold, running a program with the correct input files yields the correct (and expected) output. Yay me.
[1nickt]: Got a MacBook and am expected to develop directly on it, ironic given the recent thread about that.
[marto]: Corion, some not too serious issues with the kids, hopefully, other than that just dealing with commuting by car again in the winter, not much fun so far, and there's no real 'bad' weather yet :)

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