PHP study notes_PHP tutorial
Here we collect some knowledge points encountered in the process of learning PHP.
1 ,reset() rewinds the internal pointer of array to the first element and returns the value of the first array element. 2.PHP is not licensed under the GPL, but its own license allows redistribution of code and/or binaries. 3. Internally, PHP stores the data and type owned by the variable separately. Types are stored in separate tables. Whenever an expression containing a different type occurs, PHP automatically determines what the programmer wants to do, changes the type in the table, and automatically evaluates the expression. 4,=== operator (yes, there are three equal signs). The difference is that this operator compares both the value and the type of the data. 5. User-defined functions are very expensive in terms of using CPU and memory resources. This is mainly because PHP is interpreted and loosely typed.
6, Do not automatically wrap lines...>/textarea>Automatically wrap lines...>/textarea>
7, We often encounter script programs that fail to find multi-threaded library files. At this time, you should check whether MIT-pthreads has been installed in the system. If not, then install the software. Linux users must install LINUXThreads. These library files are critical to MySQL's multi-threaded running mode (that is, running multiple versions of itself).
8,The environment variables are not hashed into the $HTTP_ENV_VARS[]. To access;environment variables, you can use getenv() instead.
9,Applet is a small program written in Java. It can be embedded in HTML just like images. :
DHTML is similar to a scripting language. It is also interpreted by the browser to generate HTML code representing the content of the page. The only difference is that DHTML can have some additional features, such as making the page functional and using absolute coordinates to accurately position text and pictures.
10. When W3C (The World Wide Web Consortium) promulgated the HTML4 standard in 1997, it also announced the first standard for style sheets, CSS1
The definition of CSS is composed of three parts: selector (selector) ), properties and values of properties. The basic format is as follows: selector {property: value}
11. Here are several common events (more events are used, please check the relevant information): onClick: mouse click event. (Refers to when the mouse is pressed and then released.) onDblClick: Mouse double-click event. (Refers to the mouse being pressed quickly, released, and pressed again.) onMouseDown: Mouse press event. (Occurs when the mouse is pressed.) onMouseUp: Mouse release event. (Refers to the mouse from the pressed state to the bounced state.) onMouseMove: Mouse move event. (Refers to moving the mouse on a specific element.) onMouseOver: Mouse over event. (It means that it occurs when the pointer moves from the outside world to the element.) onMouseOut: mouse leaves event. (Occurs when the mouse leaves a specific element.) onLoad: loading event. (Occurs when the image or page ends loading.) onUnload: Unload event. (Occurs when a visitor leaves the page.) onScroll: Scroll bar scroll event. (Generated when the visitor uses the scroll to move up or down.)
12,L Is it a leap year? If it is a leap year, it is 1, otherwise it is 0 if ($i == 2) { if (date("L") == true) { $TotalDay = 29; } else { $TotalDay = 28; } }
13,: tells thebrowser to load http://www.htmlhelp.com/ 10 seconds after the current documenthas finished loading.
14, PHP installation: CGI and modules
#ScriptAlias /php/ "c:/php/"#AddType application/x-httpd-php .php#Action application/x-httpd-php " c:/php/php.exe"LoadModule php4_module "c:/php/sapi/php4apache2.dll"AddType application/x-httpd-php .php

PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.

PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.

Using preprocessing statements and PDO in PHP can effectively prevent SQL injection attacks. 1) Use PDO to connect to the database and set the error mode. 2) Create preprocessing statements through the prepare method and pass data using placeholders and execute methods. 3) Process query results and ensure the security and performance of the code.

PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.

PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.

PHP makes it easy to create interactive web content. 1) Dynamically generate content by embedding HTML and display it in real time based on user input or database data. 2) Process form submission and generate dynamic output to ensure that htmlspecialchars is used to prevent XSS. 3) Use MySQL to create a user registration system, and use password_hash and preprocessing statements to enhance security. Mastering these techniques will improve the efficiency of web development.

PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.

PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.


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