Question

I am trying to create an captcha with an really easy calculate sum in it.
But when I try to add + , it turns into a blank box.

Question 2 and 3

Q2 : Is hat header thing really needed and usefull ?

Q3 : $font = dirName(FILE).’/font/karate/Karate.ttf’; Can someone explain me what FILE does?

This is my code :

<?php
    ob_start();
    session_start();

    $randomnr  = rand(1, 5);
    $randomnr2 = rand(1, 5);
    $plus = '+';
    $randanswer = $randomnr + $randomnr2;
    $_SESSION['randomnr2'] = md5($randanswer); 

    $im = imagecreatetruecolor(80, 20);

    $white = imagecolorallocate($im, 255, 255, 255);
    $grey  = imagecolorallocate($im, 150, 150, 150);
    $black = imagecolorallocate($im, 0, 0, 0);

    imagefilledrectangle($im, 0, 0, 80, 25, $black);


    $font = dirName(__FILE__).'/font/karate/Karate.ttf'; //wat is dit?

    imagettftext($im, 15 , 7, 15, 19, $grey, $font, $randomnr);
    imagettftext($im, 15 , 4 , 30, 19, $grey, $font , $plus);  *PROBLEM*
    imagettftext($im, 15 , 10,  50, 19, $white, $font, $randomnr2);

    //prevent caching on client side:
    header("Expires: Wed, 1 Jan 1997 00:00:00 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");

    header ("Content-type: image/gif");
    imagegif($im);
    imagedestroy($im);

    ob_end_flush;

?>

example : http://nightcore.nl/captcha/captcha.php

If you see things I absolutely may not do , please tell me and tell me what is better to use!

Answer 1

The Karate font you are using, has no PLUS sign as a character!

see the box with 0043: it is empty.

__FILE__ is the filename and complete path of the php file now executing.
dirname(__FILE__) can be replaced with __DIR__ as of php 5.3.