public function peek()
{
if ($this->_c === 0) {
throw new TInvalidOperationException('stack_empty');
} else {
return $this->_d[$this->_c - 1];
}
}
public function testCanNotPeekAnEmptyStack() { $stack = new TStack(); try { $item = $stack->peek(); } catch (TInvalidOperationException $e) { return; } self::fail('An expected TInvalidOperationException was not raised'); }