<?php

session_start();

header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); 

header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); 

header("Cache-Control: no-store, no-cache, must-revalidate"); 

header("Cache-Control: post-check=0, pre-check=0", false);

header("Pragma: no-cache"); 



function _generateRandom($length=4)

{

    $_rand_src = array(

        array(48,57) //digits

        , array(97,122) //lowercase chars

//        , array(65,90) //uppercase chars

    );

    srand ((double) microtime() * 1000000);

    $random_string = "";

    for($i=0;$i<$length;$i++){

        $i1=rand(0,sizeof($_rand_src)-1);

        $random_string .= chr(rand($_rand_src[$i1][0],$_rand_src[$i1][1]));

    }

    return $random_string;

}

$im = @imagecreatefromjpeg("captcha.jpg"); 

$rand = _generateRandom(4);

//$rand="rahul";

$_SESSION['captcha'] = $rand;

ImageString($im, 5, 20, 8, $rand[0]."  ".$rand[2]."  ", ImageColorAllocate ($im,255, 0, 0));

ImageString($im, 5, 20, 9, "  ".$rand[1]."  ".$rand[3], ImageColorAllocate ($im, 0, 0, 0));

Header ('Content-type: image/jpeg');

imagejpeg($im,NULL,100);

ImageDestroy($im);

?>