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Course Introduction：PHP has five most commonly used hyperglobal variables, namely $\_GET, $\_POST, $\_SERVER, $\_SESSION, and $\_COOKIE. ①$\_GET is used to obtain parameters in the URL, suitable for non-sensitive data transmission such as paging and filtering, but attention should be paid to input verification; ②$\_POST is used to receive sensitive data submitted by the form, such as login information, and it is necessary to prevent SQL injection and XSS attacks; ③$\_SERVER provides information about the server and script execution environment, such as the current script name, user IP and request method, and check whether the key exists before use; ④$\_SESSION is used to maintain user status across pages, and session\_st must be called first when using it.

2025-07-18 comment 0  224

Course Introduction：Class methods automatically receive classes as the first parameter, suitable for creating or operating class-level data; static methods do not bind any parameters, suitable for functions related to classes but do not need to access classes or instances. 1. Class methods are often used as alternative constructors or processing class states, such as creating objects through string parsing; 2. Static methods are used to classify ordinary functions in classes, such as verifying whether age is legal; 3. If you need to access class states, use @classmethod, if you only need to classify tool functions, use @staticmethod, and use instance methods to access instance properties.

2025-07-08 comment 0  502

Course Introduction：Union-Based injection is an attack method in which an attacker takes advantage of the application not filtering user input correctly, inserting UNIONSELECT statements through injection points to merge query result sets to obtain sensitive data. 1. The principle is to use the UNION operator to combine multiple SELECT query results; 2. Attack examples, such as injecting UNIONSELECTusername and passwordFROMusers into URL parameters; 3. To determine whether the injection point needs to detect the number of columns, ORDERBY or NULL tests are commonly used; 4. Database names, user information, etc. can be extracted in actual combat; 5. Defense methods include using parameterized query, filtering input, minimum permission principle, hiding error information and deploying WAF.

2025-07-25 comment 0  641

Course Introduction：Array comparison is commonly used for array_intersect() and array_diff() functions. 1.array_intersect() returns the common values of the two arrays, such as finding the common role of the user; 2.array_diff() returns the values in the first array that are not in other arrays, used to detect missing or redundant items; 3. Both are based on loose comparisons and retain the original keys, pay attention to the processing of parameter order and keys; 4. Actual applications include data synchronization, permission verification and input filtering; 5. For strict type or key-value comparison, array_intersect_assoc() or array_diff_assoc() should be used; these functions improve code readability and efficiency,

2025-08-02 comment 0  590

Course Introduction：In C, static_cast and dynamic_cast are two commonly used type conversion operators that are suitable for different scenarios and are significantly different. 1.static_cast performs type conversion at compile time, suitable for conversion between basic data type conversion, upward transformation, enumeration to integer transformation, and classes with conversion constructors or type conversion operators; it does not perform runtime checks, so it is not safe for downward transformation. 2. Dynamic_cast performs type checking at runtime, mainly used for downward transformation of polymorphic types, ensuring that the conversion is legal, and returning a null pointer or throwing an exception when it fails; it is suitable for scenarios where dynamic type checking is required, but the performance overhead is high. When selecting, it should be converted according to

2025-07-21 comment 0  314

Course Elementary  13819

Course Introduction：Scala Tutorial Scala is a multi-paradigm programming language, designed to integrate various features of object-oriented programming and functional programming.

Course Elementary  82352

Course Introduction："CSS Online Manual" is the official CSS online reference manual. This CSS online development manual contains various CSS properties, definitions, usage methods, example operations, etc. It is an indispensable online query manual for WEB programming learners and developers! CSS: Cascading Style Sheets (English full name: Cascading Style Sheets) is an application used to express HTML (Standard Universal Markup Language).

Course Elementary  13173

Course Introduction：SVG is a markup language for vector graphics in HTML5. It maintains powerful drawing capabilities and at the same time has a very high-end interface to operate graphics by directly operating Dom nodes. This "SVG Tutorial" is intended to allow students to master the SVG language and some of its corresponding APIs, combined with the knowledge of 2D drawing, so that students can render and control complex graphics on the page.

Course Elementary  24624

Course Introduction：In the "AngularJS Chinese Reference Manual", AngularJS extends HTML with new attributes and expressions. AngularJS can build a single page application (SPAs: Single Page Applications). AngularJS is very easy to learn.

Course Elementary  27483

Course Introduction：Go is a new language, a concurrent, garbage-collected, fast-compiled language. It can compile a large Go program in a few seconds on a single computer. Go provides a model for software construction that makes dependency analysis easier and avoids most C-style include files and library headers. Go is a statically typed language, and its type system has no hierarchy. Therefore users do not need to spend time defining relationships between types, which feels more lightweight than typical object-oriented languages. Go is a completely garbage-collected language and provides basic support for concurrent execution and communication. By its design, Go is intended to provide a method for constructing system software on multi-core machines.