gistfile1.php

<?php

// Alternative to large switch statements
// ----
$dayFunctions = array(
    
  1 => function() {
    // do stuff
    return "something";
  },
  
  2 => function() {
    // do stuff
    return "something";
  },
 
  // ...
 
  15 => function() {
    // pay people
    return "something";
  },
 
  30 => function() {
    // do stuff
    return "something";
  },
);
 
$res = array_key_exists( $dayOfTheMonth, $dayFunctions ) ? $dayFunctions[$dayOfTheMonth]() : null;