การสร้างและใช้งานคลาส (class) และออปเจค (object)

class stack {
var $arrays;
var $size;

function stack() { // class constructor
$this->size = 0;
unset($this->arrays);
}

function push($elem) { // put an element on stack
$this->arrays[$this->size] = $elem;
$this->size++;
}

function get_size() { // get number of elements stored
return $this->size;
}

function is_empty() { // is stack empty ?
return ($this->size == 0) ? true : false;
}

function pop() { // retrieve an element from the top of stack
if ( $this->is_empty() == false ) {
$this->size–;
return $this->arrays[$this->size];
}
else
return 0;
}
}

$inst = new stack; // create an object from stack class
echo “initial stack size=”.($inst->get_size()),”<BR>\n”;

for ($i=0; $i < 10; $i++) {
$inst->push( ($i*7)%11 );
}
echo “current stack size=”.($inst->get_size()),”<BR>\n”;

while (! $inst->is_empty() ) {
echo “pop “.$inst->pop(),”<BR>\n”;
}

echo “stack is “.($inst->is_empty() ? “empty.” : “not empty.”).”<BR>\n”;

$inst = 0; // unuse this instance of class stack
?>

class stack {
var $arrays;
var $size;

function stack() {
echo “DEBUG> stack constructor<BR>\n”;
$this->size = 0;
unset($this->arrays);
}

function push($elem) {
$this->arrays[$this->size] = $elem;
$this->size++;
}

function get_size() {
return $this->size;
}

function is_empty() {
return ($this->size == 0) ? true : false;
}

function pop() {
if ( $this->is_empty() == false ) {
$this->size–;
return $this->arrays[$this->size];
}
else
return 0;
}
}

// class LimitedStack is derived from class stack.

class LimitedStack extends stack {
var $max_size;

function LimitedStack ($capacity = 10) {
$this->stack(); // call stack’s constructor explicitly.
echo “DEBUG> LimitedStack constructor<BR>\n”;
$this->max_size = $capacity;
}

function is_full() {
return ($this->max_size <= $this->size) ? true : false;
}

function push($elem) {
if ($this->is_full() == false) {
$this->arrays[$this->size] = $elem;
$this->size++;
}
else {
echo “stack is full!\n”;
}
}
}

$inst = new LimitedStack(5);
echo “initial stack size=”.($inst->get_size()),”<BR>\n”;
for ($i=0; $i < 10; $i++) {
if (! $inst->is_full() ) {
$inst->push( ($i*7)%11 );
}
else break;
}
echo “current stack size=”.($inst->get_size()),”<BR>\n”;
echo “stack is “.($inst->is_empty() ? “empty.” : “not empty.”).”<BR>\n”;

class MyObj {
var $id;

function MyObj( $set_id) {
// $id = $set_id; <– this does’t work if you forget to use $this
$this->id = $set_id;
}

function show() {
echo “hello world $this->id<BR>\n”;
}
}

// can create the array of objects
$obj_array = array();
$obj_array[] = new MyObj(1);
$obj_array[] = new MyObj(2);
$obj_array[] = new MyObj(3);

// To access each object we must use help variable like follows:
for($i=0; $i < count($obj_array); $i++) {
$tmp = $obj_array[$i];
$tmp->show();
}

?>