How to use the return value of php recursive function

functiontest($i)
{
$i-=4; if($i<3)
{
return $i;
}
else
{
test($i) ;
}
}
echotest(30);
?>

The above code seems to have no problem, but in fact there is a problem in else. The test executed here has no return value, although the condition $i is met

The following method uses PHP recursive functions and returns values. Pay attention to the difference between the comments in the code and the above code:

function test($i)
{
$i-=4; if($i<3)
{
return $i;
}
else
{
return test( $i);//Add return and let the function return the value
}
}
echotest(30);
?>