foreach $hash{key} (@array){
    ## The value of $hash{key} will be the $array[x] value.
    ## ...
  }

##</code><code>##


  my %hash = ( key => 'value');
  
  my $k_ref = \$hash{key} ;
  *{'main::val'} = $k_ref ; ## To avoid $$k_ref
  
  print "val: <$val>\n" ;
  print "key: <$hash{key}>\n" ;
  $val = 'test' ;
  print "val: <$val>\n" ;
  print "key: <$hash{key}>\n" ;


##</code><code>##


  my %hash = ( key => 'value');
  
  my $k_ref = \$hash{key} ;
  *{'main::val'} = $k_ref ;
  
  my @array = (0..5) ;

  print "val: <$val>\n" ;
  print "key: <$hash{key}>\n" ;

  
  foreach $val ( @array ) {
    print "for>> val: <$val>\n" ;
    print "for>> key: <$hash{key}>\n" ;
  }

  print "val: <$val>\n" ;
  print "key: <$hash{key}>\n" ;


##</code><code>##

for>> val: <0>
for>> key: <value>
for>> val: <1>
for>> key: <value>
for>> val: <2>
for>> key: <value>
...

##</code><code>##

for>> val: <0>
for>> key: <0>
for>> val: <1>
for>> key: <1>
for>> val: <2>
for>> key: <2>
...

##</code><code>##

  my @array = (1..5) ;
  print "@array\n" ;
  foreach my $array_i ( @array ) { $array_i *= 10 ;}
  print "@array\n" ;

##</code><code>##

  my %hash = ( key => 'value');
  my @array = (0..5) ;
  
  foreach my $val ( @array ) {
    $hash{key} = $val ;
    print "for>> val: <$val>\n" ;
    print "for>> key: <$hash{key}>\n" ;
  }