I have another solution using grep but its kinda weird....
@array = (..................); #your array here
$i=1;
eval{
grep { (/$element/o && die ) or ++$i } @array;
};
print "index of $element = $i\n"; #prints the index of $element.. If $i > scalar(@array), element not found.
-- Ankur
Manav Mathur wrote:
Rob, In your solution
$hash{'pqr'} will return 3. - iniitalize $i with 1
or
-
%hash=map{$_=>[EMAIL PROTECTED];
Manav
|-----Original Message-----
|From: Rob Napier [mailto:[EMAIL PROTECTED]
|Sent: Thursday, January 27, 2005 2:06 PM
|To: Richard Chycoski
|Cc: Mallik; Perl-Trolls; beginners@perl.org
|Subject: Re: How to find the Index of an element in array?
|
|
|In terms of time efficiency, if you only need one lookup, the linear |walk is almost certainly faster, since you don't have to hash the entire |list. You can stop as soon as you find the answer (which you expect to |be half-way down the list). But the speed difference is almost certainly |negligable. In terms of space efficiency the array is much smaller too |which matters if the hash gets particularly large (large enough that the |speed difference isn't negligable).
|
|I agree with "depending on what else you need to do with your data." If |a list is more natural for the data, definitely leave it in a list and |just walk it. If you need to do a lot of lookups (or other hash-like |things), you can hash the list as Richard suggests pretty easily:
|
|my $i = 0;
|my %hash = map { $_ => $i++ } @list;
|print $hash{$search};
|
|And of course the above is short and simple, so maybe that's nice even |if you're only doing it once and don't mind being slower and bigger |(memorywise).
|
|If you want to stay with a fast linear search, there have been a couple |of good suggestions. Tapasranjan's version is close, but does too much |searching. You should do a 'last' after you've found the data. Arjun's |solution is good, or you can do this kind of shortened form:
|
|my $search = 'pqr';
|for(my $i = 0; $i < @arr; $i++)
|{
| ($arr[$i] eq $search) && do { print "index is == $i\n"; last }
|}
|
|Note that in this form, $i is not valid outside the loop. You'll need to |move the "my $i" outside the for() loop if you need it later in the code.
|
|-RobN
|
|Richard Chycoski wrote:
|> You would have to 'walk' the whole array, which is rather inefficient. |> However, depending on what else you need to do with your data, a hash |> could do better than an array:
|> |> %myhash = ('abc'=>1, 'xyz'=>2, 'mno'=>3, 'pqr'=>4, 'stu'=>5, 'sdfd'=>6);
|> |> and then
|> $myhash{ 'pqr') wiil return 4.
|> |> - Richard
|> |> |> Mallik wrote:
|> |>> I need to find the index of a particular element in array.
|>> For eg.,
|>> @arr = ('abc', 'xyz', 'mno','pqr','stu','sdfd');
|>>
|>> I want to find the index of the element 'pqr' which is 4.
|>>
|>> Any function/code to achieve this.
|>>
|>> Thanks in advance,
|>> Mallik.
|>> |>>
|> |
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