How to create a verification code image using PHP?
Sep 13, 2023 am 11:40 AM
How to create a verification code image using PHP?
Verification code (CAPTCHA) is a commonly used method to verify whether the user is a human rather than a machine. On websites, we often see verification code images, which require users to enter random characters or numbers displayed on the image to complete operations such as login, registration, and commenting. This article will introduce how to use PHP to create a verification code image and provide specific code examples.
1. PHP GD library
To create a verification code image, we need to use PHP's GD library. The GD library is an extension library for image processing. It provides a series of functions for creating, processing and outputting images. First, we need to ensure that the GD library is enabled on the server. You can check the settings of the GD library by executing the phpinfo() function in the code.
If the GD library is enabled, you can start creating verification code images.
2. Create a verification code image
The main steps to create a verification code image include generating random strings, creating images, drawing interference lines and noise points, and outputting images.
- Generate a random string
First, we need to generate a random string as the content of the verification code. You can use the mt_rand() function to generate a random sequence of numbers or letters of a specified length, as shown below:
$length = 6; // 驗證碼長度
$chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$code = '';
for ($i = 0; $i < $length; $i++) {
$code .= $chars[mt_rand(0, strlen($chars) - 1)];
}- Create a picture
Next , we need to create a blank verification code image. You can use the imagecreate() function to create an image with a specified width and height, as shown below:
$width = 120; // 圖片寬度 $height = 40; // 圖片高度 $image = imagecreate($width, $height);
- Set the background color and text color
us You can use the imagecolorallocate() function to set the background and text color of the image, as follows:
$bg_color = imagecolorallocate($image, 255, 255, 255); // 白色背景 $text_color = imagecolorallocate($image, 0, 0, 0); // 黑色文字
- Draw text
Use imagestring ()The function draws random strings onto the verification code image, as shown below:
$font_size = 18; // 文字大小 $x = ($width - strlen($code) * $font_size) / 2; // 文字起始位置橫坐標(biāo) $y = ($height - $font_size) / 2; // 文字起始位置縱坐標(biāo) imagestring($image, $font_size, $x, $y, $code, $text_color);
- Draw interference lines and noise points
In order to improve the performance of the verification code Safety, you can draw some interference lines and noise on the picture. You can use the imagesetpixel() function to draw noise points and the imageline() function to draw interference lines.
for ($i = 0; $i < 100; $i++) {
$x = mt_rand(0, $width - 1);
$y = mt_rand(0, $height - 1);
imagesetpixel($image, $x, $y, $text_color);
}
for ($i = 0; $i < 5; $i++) {
$x1 = mt_rand(0, $width / 2);
$y1 = mt_rand(0, $height - 1);
$x2 = mt_rand($width / 2, $width - 1);
$y2 = mt_rand(0, $height - 1);
imageline($image, $x1, $y1, $x2, $y2, $text_color);
}- Output image
Finally, we need to output the verification code image to the browser. You can use the header() function to set the Content-Type of the image, and use the imagejpeg() function to output the image to the browser.
header('Content-Type: image/jpeg');
imagejpeg($image);- Destroy image resources
Remember to destroy image resources after completing image output to save server memory.
imagedestroy($image);
3. Complete code example
The following is a complete PHP code example for creating a verification code image:
Save the above code as captcha.php and pass Access the file with a browser and you will see the generated verification code image.
Summary
This article introduces how to use the GD library and PHP to create verification code images, and provides specific code examples. By understanding the principle of generating verification code images, we can carry out customized development according to actual business needs and improve the security and reliability of user verification. Hope this article helps you!
The above is the detailed content of How to create a verification code image using PHP?. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
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
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
PHP calls AI intelligent voice assistant PHP voice interaction system construction
Jul 25, 2025 pm 08:45 PM
User voice input is captured and sent to the PHP backend through the MediaRecorder API of the front-end JavaScript; 2. PHP saves the audio as a temporary file and calls STTAPI (such as Google or Baidu voice recognition) to convert it into text; 3. PHP sends the text to an AI service (such as OpenAIGPT) to obtain intelligent reply; 4. PHP then calls TTSAPI (such as Baidu or Google voice synthesis) to convert the reply to a voice file; 5. PHP streams the voice file back to the front-end to play, completing interaction. The entire process is dominated by PHP to ensure seamless connection between all links.
How to use PHP to build social sharing functions PHP sharing interface integration practice
Jul 25, 2025 pm 08:51 PM
The core method of building social sharing functions in PHP is to dynamically generate sharing links that meet the requirements of each platform. 1. First get the current page or specified URL and article information; 2. Use urlencode to encode the parameters; 3. Splice and generate sharing links according to the protocols of each platform; 4. Display links on the front end for users to click and share; 5. Dynamically generate OG tags on the page to optimize sharing content display; 6. Be sure to escape user input to prevent XSS attacks. This method does not require complex authentication, has low maintenance costs, and is suitable for most content sharing needs.
How to use PHP combined with AI to achieve text error correction PHP syntax detection and optimization
Jul 25, 2025 pm 08:57 PM
To realize text error correction and syntax optimization with AI, you need to follow the following steps: 1. Select a suitable AI model or API, such as Baidu, Tencent API or open source NLP library; 2. Call the API through PHP's curl or Guzzle and process the return results; 3. Display error correction information in the application and allow users to choose whether to adopt it; 4. Use php-l and PHP_CodeSniffer for syntax detection and code optimization; 5. Continuously collect feedback and update the model or rules to improve the effect. When choosing AIAPI, focus on evaluating accuracy, response speed, price and support for PHP. Code optimization should follow PSR specifications, use cache reasonably, avoid circular queries, review code regularly, and use X
PHP creates a blog comment system to monetize PHP comment review and anti-brush strategy
Jul 25, 2025 pm 08:27 PM
1. Maximizing the commercial value of the comment system requires combining native advertising precise delivery, user paid value-added services (such as uploading pictures, top-up comments), influence incentive mechanism based on comment quality, and compliance anonymous data insight monetization; 2. The audit strategy should adopt a combination of pre-audit dynamic keyword filtering and user reporting mechanisms, supplemented by comment quality rating to achieve content hierarchical exposure; 3. Anti-brushing requires the construction of multi-layer defense: reCAPTCHAv3 sensorless verification, Honeypot honeypot field recognition robot, IP and timestamp frequency limit prevents watering, and content pattern recognition marks suspicious comments, and continuously iterate to deal with attacks.
How to use PHP to combine AI to generate image. PHP automatically generates art works
Jul 25, 2025 pm 07:21 PM
PHP does not directly perform AI image processing, but integrates through APIs, because it is good at web development rather than computing-intensive tasks. API integration can achieve professional division of labor, reduce costs, and improve efficiency; 2. Integrating key technologies include using Guzzle or cURL to send HTTP requests, JSON data encoding and decoding, API key security authentication, asynchronous queue processing time-consuming tasks, robust error handling and retry mechanism, image storage and display; 3. Common challenges include API cost out of control, uncontrollable generation results, poor user experience, security risks and difficult data management. The response strategies are setting user quotas and caches, providing propt guidance and multi-picture selection, asynchronous notifications and progress prompts, key environment variable storage and content audit, and cloud storage.
PHP realizes commodity inventory management and monetization PHP inventory synchronization and alarm mechanism
Jul 25, 2025 pm 08:30 PM
PHP ensures inventory deduction atomicity through database transactions and FORUPDATE row locks to prevent high concurrent overselling; 2. Multi-platform inventory consistency depends on centralized management and event-driven synchronization, combining API/Webhook notifications and message queues to ensure reliable data transmission; 3. The alarm mechanism should set low inventory, zero/negative inventory, unsalable sales, replenishment cycles and abnormal fluctuations strategies in different scenarios, and select DingTalk, SMS or Email Responsible Persons according to the urgency, and the alarm information must be complete and clear to achieve business adaptation and rapid response.
Beyond the LAMP Stack: PHP's Role in Modern Enterprise Architecture
Jul 27, 2025 am 04:31 AM
PHPisstillrelevantinmodernenterpriseenvironments.1.ModernPHP(7.xand8.x)offersperformancegains,stricttyping,JITcompilation,andmodernsyntax,makingitsuitableforlarge-scaleapplications.2.PHPintegrateseffectivelyinhybridarchitectures,servingasanAPIgateway
PHP integrated AI speech recognition and translator PHP meeting record automatic generation solution
Jul 25, 2025 pm 07:06 PM
Select the appropriate AI voice recognition service and integrate PHPSDK; 2. Use PHP to call ffmpeg to convert recordings into API-required formats (such as wav); 3. Upload files to cloud storage and call API asynchronous recognition; 4. Analyze JSON results and organize text using NLP technology; 5. Generate Word or Markdown documents to complete the automation of meeting records. The entire process needs to ensure data encryption, access control and compliance to ensure privacy and security.
