Re: Grep uniqueness issue

On Jul 29, jason_normandin@xxxxxxxxxxx said:

I am having an odd problem using grep to ensure an array only contains distinct entries.

You should probably use a hash (along with your array, if you need to keep the order they're in) to ensure unique-ness.

support01-FastEthernet1/0
support01-RH
jnormandin-p370-1691-SH-Cpu-2
jnormandin-p370-1691-SH

I am trying to create an ARRAY containing each of these entries only once (a distinct list). I am using a grep statement:

push @pingErrorsName, $element if (! grep (/\b$element\b/, @pingErrorsName));

There's NO reason to use a regex here at all. You don't want $element to be treated like a regex (since it's just a string). If you were gonna use grep(), you should just do

  push @pingErrorsName, $element if !grep $_ eq $element, @pingErrorsName;

But I suggest you use a hash:

  push @pingErrorsName, $element if !$uniq{$element}++;

Read 'perldoc -q uniq' for more information.

* Where $element contains one of the above names in the list and @pingErrorsName is the distinct list of elements.

What I am finding is that the array will contain all of the correct entries except: jnormandin-p370-1691-SH. It appears as though the grep is matching jnormandin-p370-1691-SH to the jnormandin-p370-1691-SH-Cpu-2 string (as it is a substring of the second one).

Well, YES. That's because \b matches word boundaries. Between the 'H' and the '-' is a word boundary.

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