Tutorial on writing a pure digital verification code in PHP
Now let’s talk about the simple pure digital verification code.
If you are a beginner, it is recommended to follow the comments //numbers of my code step by step. The easiest way is to copy the entire code.
Create a new captcha.php:
<?php //11>设置session,必须处于脚本最顶部 session_start();
/*$image = imagecreatetruecolor(100, 30);
//1>设置验证码图片大小的函数
//5>设置验证码颜色 imagecolorallocate(int im, int red, int green, int blue);
$bgcolor = imagecolorallocate($image,255,255,255); //#ffffff
//6>区域填充 int imagefill(int im, int x, int y, int col) (x,y) 所在的区域着色,col 表示欲涂上的颜色 imagefill($image, 0, 0, $bgcolor); //10>设置变量 $captcha_code = "";*/
//7>生成随机数字 for($i=0;$i<4;$i++){ //设置字体大小 $fontsize = 6; //设置字体颜色，随机颜色 $fontcolor = imagecolorallocate($image, rand(0,120),rand(0,120), rand(0,120));
//0-120深颜色 //设置数字 $fontcontent = rand(0,9); //10>.=连续定义变量 $captcha_code .= $fontcontent; //设置坐标 $x = ($i*100/4)+rand(5,10); $y = rand(5,10);
imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor); } //10>存到session $_SESSION['authcode'] = $captcha_code; //8>增加干扰元素，设置雪花点 for($i=0;$i<200;$i++){
//设置点的颜色，50-200颜色比数字浅，不干扰阅读 $pointcolor = imagecolorallocate($image,rand(50,200), rand(50,200), rand(50,200));
//imagesetpixel — 画一个单一像素 imagesetpixel($image, rand(1,99), rand(1,29), $pointcolor); } //9>增加干扰元素，设置横线 for($i=0;$i<4;$i++){ //设置线的颜色
$linecolor = imagecolorallocate($image,rand(80,220), rand(80,220),rand(80,220)); //设置线，两点一线 imageline($image,rand(1,99), rand(1,29),rand(1,99), rand(1,29),$linecolor); }
//2>设置头部，image/png header('Content-Type: image/png'); //3>imagepng() 建立png图形函数 imagepng($image); //4>imagedestroy() 结束图形函数 销毁$image imagedestroy($image);
接着就是静态页的代码了：index.html
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional
//EN" "、www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="
<head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>无标题文档</title>
</head><body><form method="post" action="./form.php">
<p>验证码: <img id="captcha_img" border='1' src='./captcha.php?r=echo rand(); ? alt="Tutorial on writing a pure digital verification code in PHP" >' style="max-width:90%" />
<a href="javascript：void(0)" onclick="document.getElementById('captcha_img').src='./captcha.php?r='+Math.random()">换一个?</a> </p> <P>请输入验证码:<input type="text" name='authcode' value=''/></p> <p><input type='submit' value='提交' style='padding:6px 5px;'/></p></form></body></html>
从index.html可以看到，提交的表单是到form.php的，所以还要有一个判断的form.php代码：
<?php header("Content-Type:text/html;charset=utf-8");
//设置头部信息 //isset()检测变量是否设置 if(isset($_REQUEST['authcode'])){
session_start(); //strtolower()小写函数 if(strtolower($_REQUEST['authcode'])== $_SESSION['authcode']){
//跳转页面 echo "<script language=\"javascript\">"; echo "document.location=\"./form.php\"";
echo "</script>"; }else{ //提示以及跳转页面 echo "<script language=\"javascript\">";
echo "alert('输入错误!');"; echo "document.location=\"./form.php\""; echo "</script>"; }
exit();
}The above is the detailed content of Tutorial on writing a pure digital verification code in PHP. For more information, please follow other related articles on the PHP Chinese website!
How does PHP identify a user's session?May 01, 2025 am 12:23 AMPHPidentifiesauser'ssessionusingsessioncookiesandsessionIDs.1)Whensession_start()iscalled,PHPgeneratesauniquesessionIDstoredinacookienamedPHPSESSIDontheuser'sbrowser.2)ThisIDallowsPHPtoretrievesessiondatafromtheserver.
What are some best practices for securing PHP sessions?May 01, 2025 am 12:22 AMThe security of PHP sessions can be achieved through the following measures: 1. Use session_regenerate_id() to regenerate the session ID when the user logs in or is an important operation. 2. Encrypt the transmission session ID through the HTTPS protocol. 3. Use session_save_path() to specify the secure directory to store session data and set permissions correctly.
Where are PHP session files stored by default?May 01, 2025 am 12:15 AMPHPsessionfilesarestoredinthedirectoryspecifiedbysession.save_path,typically/tmponUnix-likesystemsorC:\Windows\TemponWindows.Tocustomizethis:1)Usesession_save_path()tosetacustomdirectory,ensuringit'swritable;2)Verifythecustomdirectoryexistsandiswrita
How do you retrieve data from a PHP session?May 01, 2025 am 12:11 AMToretrievedatafromaPHPsession,startthesessionwithsession_start()andaccessvariablesinthe$_SESSIONarray.Forexample:1)Startthesession:session_start().2)Retrievedata:$username=$_SESSION['username'];echo"Welcome,".$username;.Sessionsareserver-si
How can you use sessions to implement a shopping cart?May 01, 2025 am 12:10 AMThe steps to build an efficient shopping cart system using sessions include: 1) Understand the definition and function of the session. The session is a server-side storage mechanism used to maintain user status across requests; 2) Implement basic session management, such as adding products to the shopping cart; 3) Expand to advanced usage, supporting product quantity management and deletion; 4) Optimize performance and security, by persisting session data and using secure session identifiers.
How do you create and use an interface in PHP?Apr 30, 2025 pm 03:40 PMThe article explains how to create, implement, and use interfaces in PHP, focusing on their benefits for code organization and maintainability.
What is the difference between crypt() and password_hash()?Apr 30, 2025 pm 03:39 PMThe article discusses the differences between crypt() and password_hash() in PHP for password hashing, focusing on their implementation, security, and suitability for modern web applications.
How can you prevent Cross-Site Scripting (XSS) in PHP?Apr 30, 2025 pm 03:38 PMArticle discusses preventing Cross-Site Scripting (XSS) in PHP through input validation, output encoding, and using tools like OWASP ESAPI and HTML Purifier.
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment
DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
SublimeText3 English version
Recommended: Win version, supports code prompts!
MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.
