In PHP 4 constructors had the same name as the class itself. 

<?php
class banana_v4 {
    function banana_v4() {
        echo "peel..peel..";
        echo "\n<br />\n";
    }

    function eat() {
        echo "chewy..chewy..";
        echo "\n<br />\n";
    }
}

$b = new banana_v4();
$b->eat();
?>
Output
chewy..chewy..
In PHP 5 constructors are unified, under the name __construct(). 

<?php
class banana_v5 {
    function __construct() {
        echo "peel..peel..";
        echo "\n<br />\n";
    }

    function eat() {
        echo "chewy..chewy..";
        echo "\n<br />\n";
    }
}

$b = new banana_v5();
$b->eat();
?>
Output
peel..peel..
chewy..chewy..