<?php
class MathCaptchaAction extends CCaptchaAction
{
	protected function generateVerifyCode()
	{
		return mt_rand((int)$this->minLength, (int)$this->maxLength);
	}

	public function renderImage($code)
	{
		parent::renderImage($this->getText($code));
	}

	protected function getText($code)
	{
		$code = (int)$code;
		$rand = mt_rand(1, $code-1);
		$op = mt_rand(0, 1);
		if($op)
			return $code-$rand."+".$rand;
		else
			return $code+$rand."-".$rand;
	}
}