Question

I am looking for search implementation on hash using perl. I have following data in my hash

%hash = {0 => "Hello", 1=> "world"}. 

Now i want to search the hash using the values (means world and hello) and return corresponding key.

Example: I want to search for world and the result should be 1

Answer 1

Iterate of the keys of the hash with a for ( keys %hash ) ... statement and check the values as you go. If you find what you are looking for, return

my $hash = { 0 => "World", 1 => "Hello" };

for ( keys %$hash ) {
    my $val = $hash->{$_};
    return $_ if $val eq 'World'; # or whatever you are looking for
}

another option would be to use while ( ... each ... )

my $hash = { 0 => "World", 1 => "Hello" };

while (($key, $val) = each %$hash) {
    return $key if $val eq 'World'; # or whatever you are looking for
}

the use of { } literal creates a hash reference and not a hash

$h = { a => 'b', c => 'd' };

to create a literal hash you use ( )

%h = ( a => 'b', c => 'd' );

execution of while ... each on hashref

$h = { a => 'b', c => 'd' };
print "$k :: $v\n" while (($k, $v) = each %$h );  

c :: d
a :: b