title: Use of inintialized value $ in concatenation (.) Perl
body: <pre><code>use warnings;
  
  $a = 5; 
  $c = 3;
  $i;
  $x = time();
  $m = 32;
  $caracter_aleatorio;
  @caracteres = (A..Z);
  print "Ingrese la cantidad de letras que desea generar=&gt; ";
  $n = &lt;STDIN&gt;; 
  
  sub generadorMultiplicativo{  
          $numAleatorio = ((($a*$x) + $c) % $m);  
          $x = $numAleatorio;
  }
  
  for($i=1;$i&lt;=$n;$i++){   
        &amp;generadorMultiplicativo();
        $caracter_aleatorio = $caracteres[$numAleatorio];
          if($numAleatorio == 0){
         $numAleatorio++;
         }
      if($numAleatorio &gt; 26){
         $numAleatorio = $numAleatorio - 5;
      }
  
       print"Letra #$i = $caracter_aleatorio\n";  
  } 
  &lt;&gt;;
  </code></pre>
  
  <p>I know this warning is when the variable doesn't have a value, but I´ve tried everything but it´s the same, it´s a generator of "random" letters.</p>
  
  <p>Could you help me?</p>