用for循环确定生成几个随机数。
用随机函数生成范围内随机数。例如rand(1,15),生成1到15之间的数字。
用16位进制函数把生成数字字母化。dechex(rand(1,15))。
用.=运算来保存几个数字。
把生成好的随机数放到$_SESSION[变量]。等将来跟用户提交的内容比较。
2,创建图片
用图片创建函数确定,所创建的图片大小。
例如$im = imagecreatetruecolor(100,30);其中坐标100,30是以网页左上角为原点,$im为图片变量了。
3,设置颜色
使用函数 创建背景色。例如$bg = imagecolorallocate($im,0,0,0);其中0,0,0是三原色数字,$im为上面创建的图片
使用函数 创建字体色。例如$te = imagecolorallocate($im,255,255,255);
4,把字符写在图像左上角
使用函数 imagestring()吧字符写在图像。例如imagestring($im,5,0,0,$rand,$te);$im为上面创建的图片,5是显示方式,0,0
是坐标,$te是字体颜色
5,输出图像
使用函数 header("Content-type:image/jpeg");imagejpeg($im);输出图像。
----------------------------------我是华丽的分割线---------------------------
1,开启session功能;例如session_start();
2,写表单
3,表单提交的验证码 数据 与上面的$_SESSION[变量]比较
相等,验证正确。
不相等,则错误。

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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