Help needed,oo of php newbie

[ujjwal]

Hello all,
Now my problem is that
It shows this error
Hello { () }!
Fatal error: Uncaught exception 'Exception' with message 'Invalid name value' in d:\www\class\class.Demo.php:6 Stack trace: #0 d:\www\class\testdemo.php(6): Demo->set(37) #1 {main} thrown in d:\www\class\class.Demo.php on line 6
My class.Demo.php file is
<?php
class Demo {
private $_name;
public function set($name) {
if ( !is_string($name) || strlen($name) == 0) {
throw New Exception("Invalid name value");
}
$this->_name = $name;
}
public function getname() {
return $this->_name;
}

public function sa() {
print "Hello { $this->getname() }!";
}


}
?>
and my trestdemo.php file is
<?php
require_once('class.Demo.php');
$objDemo = new Demo();
$objDemo->set('Steve');
$objDemo->sa();
$objDemo->set(37);
$objDemo->set('ujjwal');
$objDemo->sa();
?>
where am I wrong?
Plz help me

[sweatje]

37 is not a string

[Dr Livingston]

class Demo {
        private $_name;
        
        public function set($name) {
            if ( !is_string($name) || strlen($name) == 0 ) {
                throw New Exception("Invalid name value");
            }
            $this->_name = $name;
        }

        public function getname() {
            return $this->_name;
        }
    
        public function sa() {
            print "Hello { $this->getname() }!";
        }
    }
    
    require_once('class.Demo.php');
    $objDemo = new Demo();
    try {
        $objDemo->set('Steve');
        $objDemo->sa();
        $objDemo->set('37'); // is now a string :)
        $objDemo->set('ujjwal');
        $objDemo->sa();
    } catch( Exception $e ) {
// print out exception
        echo( $e -> getMessage() );
    }