in reply to re-initialize the hash

Maybe store your defaults separately:

my %hash_defaults = ('a'=>0 , 'e'=>0 , 'i'=>0 , 'o'=>0 , 'u'=> 0,);
my %hash = %hash_defaults;

...

# Reinitialize
%hash = %hash_defaults;

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... or restructure your loop code so that the initialization and reinitialization use the same code:

while (...) {
    my %hash = ('a'=>0 , 'e'=>0 , 'i'=>0 , 'o'=>0 , 'u'=> 0,);
    ...
};

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... or use local (but that only works for global variables, not lexical variables):

use vars '%hash';

%hash = ('a'=>0 , 'e'=>0 , 'i'=>0 , 'o'=>0 , 'u'=> 0,);
...
do {
    local %hash = %hash;
    ... make some changes
};
... changes are forgotten

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Replies are listed 'Best First'.
Re^2: re-initialize the hash
by vennila (Novice) on Apr 01, 2010 at 08:38 UTC
    Hi Monks, I found the following way. Just copy the array to values of the hash which array contains the initialized values.Is it correct? 
    
use strict;
use warnings;
use Data::Dumper;

my @array=(0,0,0);
my %hash=('a'=>1 , 'b' =>2 , 'c'=>3,);
my @values=keys%hash;
@hash{@values}=@array;
print Dumper \%hash;

    [download]
[reply]
[d/l]
      Yes, but unneccessarily complicated. Since you can assign a hash to an array and it will do the sensible thing, your code can be shortened to

      use strict;
use warnings;
use Data::Dumper;

my @array=('a',0,'b',0,'c',0);
my %hash=('a'=>1 , 'b' =>2 , 'c'=>3,);
%hash=@array;
print Dumper \%hash;

      [download]

      Your version has the advantage that if some of the keys should change, you still would reset them to 0. If you want to reset all values to 0 you don't need the array anymore:

      @hash{keys %hash}=(0) x scalar(keys %hash);

      [download]

      CORRECTION:Forgot () around the 0. And as cdarke pointed out to me the scalar is not needed as it is already in scalar context. But I tend to play safe with these things instead of trusting my memory

[reply]
[d/l]
[select]
        Yes, but unneccessarily complicated

        Using the joy of x, your code can be shortened to: 
        use strict;
use warnings;
use Data::Dumper;

my %hash=('a'=>1 , 'b' =>2 , 'c'=>3,);
my @keys = keys %hash;

@hash{@keys} = (0) x @keys;
print Dumper \%hash;

        [download]

        Update:Note the parentheses around the zero. Without them you just get a string of zeros and the other values are undef. Also, you don't need scalar because the RHS of x is already in scalar context.
[reply]
[d/l]
        Did you check that one. 
        @hash{keys %hash}=0 x scalar(keys %hash);

        [download]
        I gave me the following output as , 
        $VAR1 = {
          'c' => '000',
          'a' => undef,
          'b' => undef
        };

        [download]
        I want all the values of hash to '0'.
[reply]
[d/l]
[select]

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