Developing functions

The most difficult aspect is deciding how to break up programming logic into functions. The mechanics of developing a function in PHP, on the other hand, are quite easy. Just use the function keyword, give it a name, and follow it with parentheses.

How to do it...

1. The code itself goes inside curly braces as follows:

   function someName ($parameter)
   { 
     $result = 'INIT';
     // one or more statements which do something
     // to affect $result
     $result .= ' and also ' . $parameter;
     return $result; 
   }

2. You can define one or more parameters. To make one of them optional, simply assign a default value. If you are not sure what default value to assign, use NULL:

   function someOtherName ($requiredParam, $optionalParam = NULL)
     { 
       $result = 0;
       $result += $requiredParam;
       $result += $optionalParam ?? 0;
       return $result; 
     }

   Note

   You cannot redefine functions. The only exception is when duplicate functions are defined in separate namespaces. This definition...