use strict ; use warnings ;

  my $x = 57 ;
  print "\${x}   = '", ${x}, "'\n" ;
  print "\${'x'} = '", ${'x'}, "'\n" ;

##</code><code>##

  ${x}   = '57'
  Can't use string ("x") as a SCALAR ref while "strict refs" in use ...

##</code><code>##

  ${x}   = '57'
  Use of uninitialized value in print ...
  ${'x'} = ''

##</code><code>##

  ${x}   = '57'
  ${'x'} = '57'