Encode unwanted characters in PHP

/*from  ww w  .j a va2 s .c  o m*/
<?php
    $var="<b>XML Griffin<b>";

    var_dump(filter_var($var, FILTER_SANITIZE_STRING));

/*
  Possible options and flags:

  FILTER_FLAG_NO_ENCODE_QUOTES - This flag does not encode quotes
  FILTER_FLAG_STRIP_LOW - Strip characters with ASCII value below 32
  FILTER_FLAG_STRIP_HIGH - Strip characters with ASCII value above 127
  FILTER_FLAG_ENCODE_LOW - Encode characters with ASCII value below 32
  FILTER_FLAG_ENCODE_HIGH - Encode characters with ASCII value above 127
  FILTER_FLAG_ENCODE_AMP - Encode the & character to &amp;

*/

?>