php function

<?php
/*
can leave out ?> to execute and print at terminal.
*/

function countdown()
{
  echo "4, 3, 2, 1, ";
  return "blastoff!"; //return should always be the last line in the function
}

$return_value = countdown(); //assign function to a variable, which also invokes the function to print echo line
echo $return_value;  //then this prints the return stm

// Empty function that returns NULL
  function createVacuum(){
    return NULL; //can also leave this line out, especially the return keyword
  }

echo createVacuum() * 10; // value printed as 0