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如何在服务器端 PHP 中检查此验证码脚本的正确性？

我使用此脚本显示验证码图像并通过 ajax 进行检查。现在我也想在服务器端 PHP 中检查它。怎么做？

验证码.php

<?php
//Start a session so we can store the captcha code as a session variable.
session_start();

// Decide what characters are allowed in our string
// Our captcha will be case-insensitive, and we avoid some
// characters like 'O' and 'l' that could confuse users
$charlist = '23456789ABCDEFGHJKMNPQRSTVWXYZ'; 

// Trim string to desired number of characters - 5, say
$chars = 5;
$i = 0;
while ($i < $chars) 
{ 
  $string .= substr($charlist, mt_rand(0, strlen($charlist)-1), 1);
  $i++;
}

// Create a GD image from our background image file
$captcha = imagecreatefrompng('images/captcha.png');

// Set the colour for our text string
// This is chosen to be hard for machines to read against the background, but
// OK for humans
$col = imagecolorallocate($captcha, 0, 0, 0);

// Write the string on to the image using TTF fonts
imagettftext($captcha, 29, 1, 15, 29, $col, 'images/fonts/arial.ttf', $string);

// Store the random string in a session variable
$_SESSION['secret_string'] = $string;

// Put out the image to the page
header("Content-type: image/png");
imagepng($captcha);
?>
4

2 回答 2

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$_SESSION['secret_string']当用户提交表单匹配发布的代码时，您有验证码$_SESSION['secret_string']。

于 2012-11-22T11:17:15.367 回答
0

为了在服务器端验证验证码，您可以这样做

<?php
session_start();
//code is the name of your captcha text field
if($_SESSION['secret_string']==$_POST['code'])
echo "Captcha verfication passed..";
else
echo "Captcha verfication failed..";
?>
于 2012-11-22T11:28:12.497 回答