สอบถามหน่อยครับถ้าผมต้องการใช้ Class IntlDateFormatter ต้องทำอย่างไรครับ

<?php
$fmt = datefmt_create( "en_US" ,IntlDateFormatter::FULL,IntlDateFormatter::FULL,'America/Los_Angeles',IntlDateFormatter::GREGORIAN  );
echo "First Formatted output is ".datefmt_format( $fmt , 0);
$fmt = datefmt_create( "de-DE" ,IntlDateFormatter::FULL,IntlDateFormatter::FULL,'America/Los_Angeles',IntlDateFormatter::GREGORIAN  );
echo "Second Formatted output is ".datefmt_format( $fmt , 0);

$fmt = datefmt_create( "en_US" ,IntlDateFormatter::FULL,IntlDateFormatter::FULL,'America/Los_Angeles',IntlDateFormatter::GREGORIAN  ,"MM/dd/yyyy");
echo "First Formatted output with pattern is ".datefmt_format( $fmt , 0);
$fmt = datefmt_create( "de-DE" ,IntlDateFormatter::FULL,IntlDateFormatter::FULL,'America/Los_Angeles',IntlDateFormatter::GREGORIAN  ,"MM/dd/yyyy");
echo "Second Formatted output with pattern is ".datefmt_format( $fmt , 0);
?>