Question

Which is the recommended approach?

Using include:

// subroutine.php

echo 'hello '.$a;

// usage.php

$a = 'foo';
include 'subroutine.php';

Using function:

// subroutine.php

function subroutine ($a)
{
    echo 'hello '.$a
}

// usage.php

include 'subroutine.php';
$a = 'foo';
subroutine($a);

Since both technically work and since there is no “subroutines” in PHP unlike ASP for example. What is the best way to emulate subroutines?

Answer 1

A function is better suited for this purpose. Includes are more widely used for templating, or for when the controller calls a view.

However, your function should not echo the concatenated string. It should return it.

$a = "foo";
echo subroutine($a);

function subroutine($a) { return "hello " . $a; }

This makes your code testable.