In default function only function call without argument or value.
Example:-
Program for default functions
<?php
function call()
{
echo "Hello PHP Function";
}
call(); //calling function
?>
Call by value or argument functions
Function will be call with argument or value.
Example:-
program for call by value or argument functions
<?php
function Hello($name){
echo "Hello $name<br/>";
}
Hello(“raj");
Hello(“rajesh");
?>
Call by reference functions
Function will be call with reference variable.
The $var (single dollar) is a normal variable with the name var that stores any
value like string, integer, float, etc.
The $$var (double dollar) is a reference variable that stores the value of the
$variable inside it.