Re^2: substring problem???

GrandFather,
The problem asked is far more interesting than the real problem actually desired (last 4 chars of a string). I would submit the following as a starting point for the asked problem:

my $desired = substr($string, index($string, $tail) - 4, 4);
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It has a few obvious flaws but since the desired problem isn't the one asked, I didn't pursue it.

Cheers - L~R

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Re^3: substring problem??? by davido (Cardinal) on May 28, 2006 at 16:02 UTC
I tinkered with that too, and then abandoned it simply because it seemed to require too much status checking. If $tail isn't found in $string, index returns a -1, so you've got to check for that. And then if index() - 4 doesn't exist, you have another problem that will generate a warning, so an out of bounds check needs to be performed as well. I suspect that the substr(..., index()) method is at least as speed efficient as the regexp approach, but it's definately more cumbersome to implement. I still like the substr/index approach for its straightforwardness, but regret the implementation will probably tend to look a little unPerlish. Dave	[reply]

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Re^3: substring problem???
by davido (Cardinal) on May 28, 2006 at 16:02 UTC

I tinkered with that too, and then abandoned it simply because it seemed to require too much status checking. If $tail isn't found in $string, index returns a -1, so you've got to check for that. And then if index() - 4 doesn't exist, you have another problem that will generate a warning, so an out of bounds check needs to be performed as well. I suspect that the substr(..., index()) method is at least as speed efficient as the regexp approach, but it's definately more cumbersome to implement.

I still like the substr/index approach for its straightforwardness, but regret the implementation will probably tend to look a little unPerlish.

Dave

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