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Re^3: How to check if a variable's value is equal to a member of a list of values

by cls33 (Novice)
on Mar 25, 2013 at 15:24 UTC ( #1025324=note: print w/ replies, xml ) Need Help??


in reply to Re^2: How to check if a variable's value is equal to a member of a list of values
in thread How to check if a variable's value is equal to a member of a list of values

Seems like I'm on the right track, but this is a more elegant implementation. I was not previously familiar with the ability to suck an entire array into a hash using the @hash{@array}=() syntax.

One quick syntactical question... using this method, how would I set each hash key to a defined static value? Using something like:

@hash{@array}='MyValue';

Only seems to set the value for the first key...


Comment on Re^3: How to check if a variable's value is equal to a member of a list of values
Re^4: How to check if a variable's value is equal to a member of a list of values
by LanX (Abbot) on Mar 25, 2013 at 15:36 UTC
    > I was not previously familiar with the ability to suck an entire array into a hash

    it's called "hash slice"! see perldata#Slices

    > using this method, how would I set each hash key to a defined static value?

    assign a list of same length

    DB<156> @array=1..5 => (1, 2, 3, 4, 5) DB<157> @hash{@array} = ('my val') x @array => ("my val", "my val", "my val", "my val", "my val") DB<158> \%hash => { 1 => "my val", 2 => "my val", 3 => "my val", 4 => "my val", 5 => + "my val" }

    Cheers Rolf

    ( addicted to the Perl Programming Language)

    UPDATE

    for completeness TIMTOWTDI:

    $hash{$_}="my val" for @array

    has less of a memory footprint.

    and

     my %hash = map { $_ => "my val" } @array;

    is DRYer and makes sure the whole hash is reinitiated.

Re^4: How to check if a variable's value is equal to a member of a list of values
by choroba (Abbot) on Mar 25, 2013 at 15:37 UTC
    You have to provide a list of values on the right hand side. For example, you can try:
    @hash1{@array} = ('value') x @array; @hash2{@array} = 0 .. $#array;
    لսႽ ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ
      Hm... makes sense. But how do I handle it if I don't know the size/length of the array? Do I really have to check that and then programmatically build an array in a loop? Or is there a syntactical shortcut?
        I do not understand. In my examples, the size of the array is not hardcoded, it is dynamically computed from @array in the scalar context or $@array.
        لսႽ ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

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