Do I need to use a hash 2

[jrig]

I'm trying to pass 2 values into a function, using a foreach statement. For example

my @things = (car::grey, house::yellow, base::own);
foreach (@things){
    print "My $first is $second.\n"
}

searching for array pairs returned mostly result about hashes.
I never had to use hashes, so I know little about them. Not sure if I can use them since I don't have a 'key'. If not, how can I do this with arrays, split? I couldn't get that syntax right either. TIA-

 

[PaulTEG]

my @things = (car::grey, house::yellow, base::own);
foreach (@things){
    print "My $first is $second.\n"
}

should prolly read as

my @things = ([COLOR=red]'[/color]car::grey[COLOR=red]'[/color], [COLOR=red]'[/color]house::yellow[COLOR=red]'[/color], [COLOR=red]'[/color]base::own[COLOR=red]'[/color]);
foreach (@things){
    [COLOR=green]($first, $second)=split (/\:\:/, $-);[/color]
    print "My $first is $second.\n"
}

The green bit might need a little rework

Paul
------------------------------------
Spend an hour a week on CPAN, helps cure all known programming ailments ;-)

 

[KevinADC]

my @things = (car::grey, house::yellow, base::own);
foreach (@things){
    my ($first, $second) = split(/::/);
    print "My $first is $second.\n"
}

my %things = (car,grey,house,yellow,base,own);
foreach my $key (keys %things){
    print "My $key is $things{$key}.\n"
}

- Kevin, perl coder unexceptional!

 

[max1x]

Paul,

Is this

($first, $second)=split (/\:\:/, $-);

suppoed to be:

($first, $second)=split (/\:\:/, $_);

 

[KevinADC]

on behalf of Paul: yes.

$- is used with perls formatting commands to print reports and such. It's some kind of counter if I remember correctly.

- Kevin, perl coder unexceptional!

 

[PaulTEG]

oops, :-o

Paul
------------------------------------
Spend an hour a week on CPAN, helps cure all known programming ailments ;-)

 

[jrig]

Thanks Kevin and Paul - I forgot to add the '$_' to the end of my split statement, which is why I couldn't get it to work. For some reason I was thinking it was implied.

Any advantage to use a hash here? '@things' is pretty small. If I'm not mistaken hashes are best for referencing indexes, or keys which can point to a value. Something not very practical in an array. Correct?

Thanks again all-

 

[PaulTEG]

$_ is implied to split, I just always use it ;-)

Hashes rule, I find them best for a number of things, including deduping, or counting occurences of list members in arrays, as well as for their indexing function

HTH

Paul
------------------------------------
Spend an hour a week on CPAN, helps cure all known programming ailments ;-)

 

[ishnid]

Note that all hash keys are unique, so if you have multiple entries in your array that start with "car::", a hash won't be appropriate, as the previous one will be lost whenever another is added.

 

[PaulTEG]

a 2-dimensional hash would be appropriate though ;-)
$hash{$item}{$color}

Paul
------------------------------------
Spend an hour a week on CPAN, helps cure all known programming ailments ;-)

 

[ishnid]

. . . or possibly a hash of arrays.

$hash{car} = [ 'red', 'green' ];

 

[KevinADC]

Any advantage to use a hash here? '@things' is pretty small. If I'm not mistaken hashes are best for referencing indexes, or keys which can point to a value. Something not very practical in an array. Correct?

If you are using key/value pairs, like "car::grey" then a hash is probably the way to go. But as ishnid has pointed out the keys must be unique. So you can't have: "car,grey, car,blue" in the same hash but you can have: car => [grey,blue] which is a hash key that contains an array as it's value.

Arrays are good when you tend to process every item in the list, especially if the array is processed over and over. Arrays are not so good if you tend to have to search through the array to find an item or items although sometimes that is necessary and should not be considered a bad thing to do.

Hashes are great for many many things, you are only limited by your imagination and experience and a few built in rules (like hash keys must be strings, etc).

- Kevin, perl coder unexceptional!